Here is a collection of Git tips that you may find useful (I did). This list will be updated as I find them (when I remember to as well)

Deleting local branches that have already been merged
git branch --merged | grep -v "\*" | xargs -n 1 git branch -d
Finding particular commits that have certain content

e.g I knew at some point in time the repository contained a file (somefile) that started with returning and executing an anonymous JavaScript function that had the signature.

(function(myvar)

Now to find commits that had that code (its easier to infer which one was first) do the following.

git grep -e '(function(myvar)' $(git rev-list --all) somedirectory/somefile

someshahashhere:somedirectory/somefile:           return (function(myvar) {
someshahashhere2:somedirectory/somefile:           return (function(myvar) {

Then its a matter of checking out the file from those commits and inspecting.

git checkout someshahashhere somedirectory/somefile

The above could would check out the first commit with a sha hash of {someshahashhere}. You now have that file as it was originally with that anonymous JavaScript function.

Git Tricks