If you need a handy chord chart to keep by your piano or keyboard, I've put together what I call The Ultimate Chord Cheat Sheet.
On the cheat sheet you'll find all of the common chords that you'll come across. This includes all major, minor, 2, 4 / sus, 6, m7, M7, 7 and add9 chords. It is sorted by letter name as well as lists chords by key.
Enjoy!