A collection of important downloads, documentation and whitepapers for Lync Server 2013, will be updated continuously. Let me know if I have missed something important. I also recommend listening to The UC Architects podcast where we will discuss tools, features and news regarding Lync and Exchange
Last updated 23.12.14

Updates

Microsoft Lync Server 2013 updates: December 2014 [updated, 11.12.14] Installation guide
Microsoft Lync 2013 updates: October 2014 [updated, 15.10.14] 
Service Pack 1 for Microsoft Office 2013 (KB2817430) 32-Bit Edition  [added, 02.03.14]
Service Pack 1 for Microsoft Office 2013 (KB2817430) 64-Bit Edition  [added, 02.03.14]
Microsoft Lync for Mac 2011 update [new, 29.10.13]
SP1 Update for Microsoft Office Web Apps Server 2013  [updated, 18.04.14] How to apply update

Deployment

Microsoft Lync Server 2013 180-Day Trial/Evaluation
Microsoft Office Web Apps Server – Moved to MSDN downloads
Language Packs for Microsoft Office Web Apps Server [new, 13.03.13]
Microsoft Lync Server 2013 Planning Tool [updated, 01.07.13]
Microsoft Lync Server 2013 Resource Kit Tools  [updated, 09.01.14]
Microsoft Lync Server 2013 Persistent Chat Resource Kit  [updated, 02.07.13]
Microsoft Lync Server 2013 Stress and Performance Tool  [Updated, 08.03.13]
Microsoft Lync Server 2013 Capacity Calculator  [updated, 01.07.13]
Microsoft Lync 2010 and 2013 Bandwidth Calculator  [new, 14.05.13]
Microsoft Lync 2013 Visio Stencil [updated, 04.10.14]
Microsoft Lync 2013 Best Practice Analyser
Unified Communications Managed API 4.0 Runtime
Exchange Server 2013 UM Language Packs [added, 17.03.13]
MVP Ken Lasko’s Dialing Rule Optimizer [added, 31.07.13]
MVP Brian Ricks’ Lync Server Design/Planning and Policies [added, 02.03.13]

Development

Lync Web Developer [new, 05.03.13]
UCMA 4.0 SDK  [new, 28.02.13]
Microsoft Lync 2013 SDK  [updated, 01.07.13]
Microsoft Lync Server 2013 Persistent Chat Server SDK  [new, 28.02.13]

Clients

Microsoft Lync for Windows 8 [added, 18.08.14]
Microsoft Lync Mobile 2013 for WP8 [updated, 10.12.14]
Microsoft Lync Mobile 2013 for iPhone [updated, 17.10.14]
Microsoft Lync Mobile 2013 for iPad [updated, 17.10.14]
Microsoft Lync Mobile 2013 for Android [updated, 19.12.14]
Microsoft Lync Basic 2013 (64 Bit) [updated, 09.07.13] Remember to install the Lync updates
Microsoft Lync Basic 2013 (32 Bit) [updated, 09.07.13] Remember to install the Lync updates
Microsoft Lync VDI 2013 plugin (64 bit) [Updated, language support, 28.02.13]
Microsoft Lync VDI 2013 plugin (32 bit) [Updated, language support, 28.02.13]

Client Tools

Microsoft Lync Meeting Update Tool (32 bit) [added, 22.01.14]
Microsoft Lync Meeting Update Tool (64 bit) [added, 22.01.14]
Profiles for Lync v2: for Lync 2010 and 2013: Easy switch between Lync users [updated, 29.09.14]
HIDnLync – Create shortcuts to change presence [added, 16.09.13] 
Lync Select Dial: Just Select and Press Hotkey to Dial With Microsoft Lync [updated, 06.02.14]
Event Zero’s Lync Agent Manager [added, 29.07.13]
LAura: Colorizes the Windows Window Color based on Lync presence [added, 31.07.13]

Third Party Applications

Espera Dashboard and Reporting Systems [added, 02.07.13]
Vytru Contacts Manager V3.3 [added, 29.07.13]
Singula Software Lync Analytics [added, 29.07.13]
Event Zero Dossier Lync reporting [added, 29.07.13]
Lync Solutions’ Security Edge Filter [added, 31.03.14]
OrbitOne’s Lync Meeting Reminder [added, 24.09.2014]

Lync Phone Edition

Microsoft Lync Phone Edition for Aastra 6721ip and Aastra 6725ip [updated, 21.10.14]
Microsoft Lync Phone Edition for HP 4110 and HP 4120 [updated, 21.10.14]
Microsoft Lync Phone Edition for Polycom CX500, Polycom CX600 and Polycom CX3000 [updated, 21.10.14]
Microsoft Lync Phone Edition for Polycom CX700 and LG-Nortel IP Phone 8540 [updated, 20.08.14]

Adoption

Lync 2013 Rollout and Adoption Success Kit (RASK) User Education and Training Resources [new, 21.03.13]
Lync 2013 Rollout and Adoption Success Kit (RASK) Core Planning Resources [new, 21.03.13]

Troubleshooting

Microsoft Lync Server 2013 Debugging Tools [Updated, 09.01.14]
Microsoft Lync Connectivity Analyzer (64 Bit) [Updated, 21.01.14]
Microsoft Lync Connectivity Analyzer (32 Bit) [Updated, 21.01.14]
Microsoft Remote Connectivity Analyzer
Microsoft Lync PreCall Diagnostics Tool  [Updated, 17.10.13]
Microsoft Network Monitor 3.4
PortQryUI – User Interface for Port Scanner [added, 11.05.13] Download Lync Config
Fiddler – Web debug tool [added, 02.05.13] Configure Fiddler for Lync Mobile sign-in troubleshooting
Lync 2013 Centralised Logging UI [new, 17.04.13]
SSL Installation Diagnostics Tool – Check your public certificate online [added, 01.08.13]
DigiCert® Certificate Utility for Windows – validate your server certificates [added, 01.08.13]
Lync ICE Warning Flag Decode [added, 13.03.14]
http://lyncvalidator.com/ [added, 23.12.14]

Management

Microsoft Lync Server 2013 Monitoring Management Pack  [updated, 18.11.14]
Microsoft Lync Server 2013 Whiteboard Archiving Viewer  [new, 27.02.13]
LUMT – Lync User Management Tool
Lync 2013 Call Pickup Group Manager [new, 14.10.13]
Lync Insights – Answering the burning questions! [new, 21.05.14]

Training

Lync sessions from TechEd Europe 2014 on Channel9 [added, 23.12.14]
Lync sessions from TechEd North America 2014 on Channel9 [added, 21.05.14]
Lync Conference 2014 Sessions on Channel9 [added, 21.05.14]
Microsoft Lync 2013 Ignite, latest ppt’s [added, 27.11.2013]
Test Drive – Lync Server 2013 VHD’s – Part 1, 2 and 3 [added, 16.09.13]
Download Free Getting Started with PowerShell 3.0 Video Series with #PowerShell [added, 29.07.13]
Download-TechEdSessions 2013 Lync sessions [added, 02.07.13]
Download all #Lync 336 and 337 Jump Start Training Videos [added, 02.07.13]
Lync Conference 2013: Slides and videos [updated, 01.01.14]
TechEd Australia 2012: Lync Sessions
Microsoft Lync 2013 Ignite Guided Labs

Documentation and Whitepapers

Microsoft Lync Server 2013 Documentation Help File [updated, 28.02.13]
Microsoft Lync Server 2013 Documentation on TechNet
Microsoft Lync Interop Programs
Microsoft Lync Qualified Hardware and Applications
Delivering Lync 2013 Real-Time Communications over Wi-Fi
Lync 2013 Headers for SIP Trunk provider billing [new, 09.05.13]
Network Planning, Monitoring, and Troubleshooting with Lync Server [updated, 23.10.13]
Microsoft Lync Room System (Beta Version) Deployment Guide [added, 02.07.13]
Lync Features Comparison Chart [added, 02.07.13]
Integrating SharePoint, Exchange, and Lync explained [added, 02.07.13]
Provisioning Guide for Lync-Skype Connectivity: Lync Server 2013 and Lync Online [added, 05.07.13]
Lync Server 2013 Reference Topologies for Enterprise Hybrid Deployments [new, 08.08.13]
Microsoft Lync Server 2013 Protocol Workloads Poster [added, 27.11.13]
Planning a Lync Server 2013 Deployment on Virtual Servers [added, 02.03.14]
Lync Server 2013 Stress Testing Guide [added, 02.03.14]
Open Specifications Posters [new, 21.05.14]
Deploying Lync in a Multi-Forest Architecture (Partner Hosted Lync with Exchange Hybrid) [new, 30.09.14]

Good blog articles explaining Lync

Lync 2013 client sign-in and DNS records recommendations [new, 08.08.13]
HTTP Proxy & Lync 2013 – URLs to exclude for proxies [new, 08.08.13]
Lync 2013 Licensing Guide [added, 29.07.13]
Validating QoS on Lync Endpoints
Microsoft Lync VDI plugin Versus the Citrix HDX Optimization Pack for Microsoft Lync
Microsoft Lync 2013 in a Virtual Desktop Infrastructure [added, 02.03.14]
Lync 2013 High Availability deep dive: Architecture [added, 02.03.14]
Improve Lync Contact Search without Sharepoint [added, 21.05.14]
Client Registry Keys [added, 23.12.14]

PowerShell Scripts

SCRIPT: Get-UnusedNumbers.ps1 [updated, 13.05.14]
SCRIPT: Set-GlobalVoiceRouting.ps1
SCRIPT: LyncLabOnline – Automated deployment of Lync Server 2013 & Exchange Server 2013  [new, 27.02.13]
SCRIPT: Backupscript-Lync_2013_v3.ps1 [updated, 26.10.14]
SCRIPT: Set-Cs2013Features.ps1 [updated, 22.12.13]
SCRIPT: New-LyncEnvReport.ps1 – Documents Lync deployments [added, 10.05.13]
SCRIPT: Get-CsConnections.ps1 – See User Connections, Client Versions [added, 01.08.13]
SCRIPT: Convert-SonusSbcConfigToWord.ps1 [new, 02.07.13]
SCRIPT: Publish-LyncContactInformation.ps1 [new, 08.08.13]
SCRIPT: Start-PomodoroSprint.ps1 [new, 14.11.13]
SCRIPT: Get-AssignedLineURI.ps1 [added, 02.03.14]
SCRIPT: Search-LineURI.ps1 [added, 02.03.14]
SCRIPT: Set-Lync2013ClientWarnings.ps1 [added, 21.05.14]
SCRIPT: Get-InstalledLyncVersion.ps1 [updated, 24.09.14]
SCRIPT: Lync Call Accounting [added, 05.08.14]