auto-versioning

So I was reading this stackoverflow post about "autoversioning" in ASP.NET MVC for CSS/JS files and was wondering what the "best" strategy is to do this. The solution provided inserts an assembly number - which means everytime you publish - it will change EVERY SINGLE file which is not ideal because if you make modifications to just 1 *.css or *.js then it will change each and every file. 1) How can it be done just for "single files" instead of using site wide assembly using modification date or something on IIS7 ? 2) Also if I have some sort of "static" asset like - http://static.domain.com

UPDATE I see that this question has become somewhat popular. It's now years into my admittedly enjoyable Git use, and I have learned a lot since then. Please , pretty please read the last paragraph before going on about your Git adventures with whatever you will have learned from this Q&A. I want to compose application build version that is automatically derived from GIT branch name I am on (when building) and the number of commits since the branch has diverged. I believe this will be unique for any commit in my GIT repository? Branch names are unique, and commits are linked to each other