I was poking around in the Services management console the other day. Every time I do this, I'm reminded that there are a lot of services registered by default on Windows. The descriptions provided for the services in the management console are pretty good but yesterday I found a page in TechNet that provided additional information about many of the default Windows services.
The TechNet page is titled System Services. The article begins with a lot of good background information about services but it was the "Descriptions of System Services" section that caught my eye. In there you'll find a list of many of the default Windows services provided in Windows Vista/Server 2008.
Anyway, not sure if you'll find the information useful but I found it interesting. Finally if you find a more recent list that includes the additional services in Windows 7 and Windows 8, I'd appreciate it if you drop me a comment.
Update: Helge Klein found the System Service documentation for Windows 7/2008 R2. Turns out they changed the title to "Threats and Countermeasures Guide: System Services" but the information (new and old) is there. Thanks, Helge.