I have been working with Team Foundation Server for around a year now and I am still finding features and I am still amazed at the extensibility of the system. The core of this extensibility is the aggressively configurable process templates. You can see a list of commercial templates on the Microsoft site, not all of them cost money though.
We have been working on our own process template, but developer are the worst people to design it. For anything more than small, inconsequential configurations you will need some serious effort, especially if you want to configure from scratch, I would not even think of that.
If you are going to configure process templates for Team Foundation Server you should do it centimeter by centimeter and do not bite off more than you can chew.
