vCheck — Great report (and report template) for vSphere, Exchange.
PowerGUI — Powershell-based GUI for AD, vSphere, Exchange, etc.
Quest AD Cmdlets — An enhanced set of AD cmdlets No longer free… :(
PowerCLI — A must-have tool for working with VMware ESXi/vSphere products.
EMS – Exchange Management Shell (which comes with Exchange Tools)
GPO Guide for Ps-Remoting / WinRM — As close to native-SSH as Windows admins are going to get.
Carbon – A DevOps powershell module with focus on removing a lot of the boilerplate for things like manipulating services, installing/validating programs, etc.
Why you should consider Invoke-WebRequest over Invoke-RestMethod
PowerShell SupportsShouldProcess Worst & Best Practices – Great read for anybody getting serious about powershell design (especially modules)
VMWare Fast Suspend/Resume
SQL Server (MSSQL)
Ola Hallengren’s SQL Server Maintenance Plan – An excellent and flexible set of backup/restore/integrity scripts.
Brent Ozar’s Hierarchy of Database Needs: The SQL Server DBA Training Plan – Great for any new or unexpected DBAs
Brent Ozar Downloads – First Aid pack, ebooks, white papers, etc.
Visual Guide to NoSQL – Good, general overview on the CAP theorem.