Here are a few quick tips n tricks to impress your friends with:

Search for a commit, even inside a deleted branch

$ git log -g --grep=search_for_something

Create tags / releases

$ git tag -am <message> <version>
$ git push --tags

Typo on last commit? No problem

$ git commit --amend

will let you edit your latest commit message

Throwing away ALL changes (WARNING: YOU MAY LOSE YOUR WORK - YOU DIDN'T LEARN THAT FROM ME. OK? OK! THX)

$ git reset --hard

Find out when a file was deleted

$ git log -1 -- views/deleted_file.rb

commit 25345bbed8f37ab5781475006a1cb8199821c19a
Author: falexandrou <fotis@example.com>
Date:   Tue Feb 3 18:16:29 2015 +0200

    remove an unused file

Restore a file that was deleted

Get the commit that the file was deleted (shown above)

git checkout 25345bbed8f37ab5781475006a1cb8199821c19a^ -- views/deleted_file.rb

Mind the ^ in the commit hash. This means we're restoring the latest revision of the file 1 commit before the commit that deleted the file

List and/or clear all items in git stash

$ git stash list
$ git stash clear