A while back (actually a year and a half since the latest update) Ray Dulski (ArtCom) and I combined efforts to write a program called GBK to help people who use the guitar, bass or keyboard (hence the name) learn chords.
This was an interesting project. Ray spent much more time than I did on the database behind it that contains all the info for the what scale/key/variation/voicings each chord contains. The end result is not bad at all and has received good feedback from the musical community.
If you are a beginner who is learning the guitar (or bass or keyboard), GBK will save you having to use endless chord books or printouts of chords.
I have occassionally tried to write music myself (seems so easy when you hear a good song and think “I can do that”) and GBK has been a great help. At least it is a great help to allow me to make correct in tune sounding chords. Writing the actual music/tune is not simple. I am still searching for the holy grail of getting a program to write pleasing sounding music automatically.
Ray is much more the muso than I am.