Markus's list hits on some of my favorites but wanted to add a plug for sublime's linters!
Depending on what type of developer you are, there are various linters (programs that run and analyze potential sources for bugs) that can be really helpful in making sure your code is up to par (clean, neat, bug free).
I have CSS Lint and JSHint Linters both installed.
Also, check out TrailingSpaces. Definitely helps curb my OCD a bit :).
