At work we use the svn $Id$-Property to track the most recent revision in our source files (particularily JavaScript files) on commit.
For smaller freelance projects at home (Web or Java) I use eclipse and local git version tracking.
I would love to add meta-data such as a timestamp or last saved revision to my source files. It doesn't matter much to me, whether the data would be added on saving, commiting or uploading a file.
A token replace method like svns $Id$ would be best, but I'm open to any other method.