Guitar Chords gives all the basic and advanced chords, helping you learn how to place your hands to play them.
It is an easy and efficient program, coming with all the instructions you are going to need.
The actual sounding of the chords would be a nice addition I guess.
Over 40000 basic and advanced chords; simple environment; TAB notation of the chords; No confusing graphics or images.
(Check also this Guitar Chords Desktop Gadget with tuner and metronome)