I inherited a farm and I need to document the solutions/features being used. At this point, I think I'll need to write some PowerShell or a console app to do this, but just wanted to throw the question out there to make sure I wasn't missing some nifty free utility.
A quick way to get a view of what is being used where is with the stsadm command enumallwebs using the addtional parameters supplied with the October 2009 Cumulative Update:
stsadm -o enumallwebs -includefeatures -includewebparts -includeeventreceivers -includesetupfiles -includecustomlistview
"Documentation Toolkit for SharePoint" can generate a Word document that extensively documents your SharePoint environment. It is a commercial application, and as such requires licensing; however a 30 days trial is available at: http://www.spdockit.com/
SPM SharePoint Manager - http://spm.codeplex.com/
Shane Young's got a pretty good blog post on how you can extract every solution package in your SharePoint 2010 farm with a PowerShell script: http://msmvps.com/blogs/shane/archive/2011/05/05/using-powershell-to-export-all-solutions-from-your-sharepoint-2010-farm-and-other-fun.aspx