Update: I don't use TFS anymore. But from the comments I can see that git-tfs is obviously the way to go nowadays.
Has anybody experience using Git as an offline solution for Team Foundation Server?
For Subversion you could use git-svn to keep a private repository with a svn backend.
I tried to use SvnBridge and git-svn to work with TFS. At first it looked promising but Visual Studio recognizes the solution as being under TFS version control and interferes during commit.
Are there other ways to combine those two?
We just decided to do this at work. Here is a blog post about how we did it.
http://blog.lozanotek.com/archive/2009/10/20/git-svn_SvnBridge_and_TFS_Source_Control.aspx
Just found this project on Github too.. this might work but I have not tried it yet.
http://github.com/spraints/git-tfs
I've started working on a tool called git-tfs, similar in some ways to git-svn.
https://github.com/git-tfs/git-tfs
I can tell you it is possible...
Also here you can find some minor details about someone with the same experience: http://blog.zobie.com/2009/04/using-git-to-avoid-problems-with-tfs/
Slightly off-topic to your question, but I have written a Powershell script that converts a TFS repository to a Git one. Might also be useful.
See my Github repo for the script
Brian Harry goes through some great detail about the new integration of Git repositories into the Team Foundation Service as well as Team Foundation Server 2013. There are quite a few interesting points he makes that are particularly important to enterprise and generally for teams who care about having a solid hosting of their Git repos:
Source: Enterprise Grade Git Repos
I'm sure it's possible, but it's going to be very rube goldberg-ian in its construction and will most likely lead to more pain than pleasure. I suggest picking a source control system and going with it.
If you need real offline support then git is awesome, but windows support is still a bit flakey.