I got this little thingy about 6 months ago, it's a great reference tool for playing piano/keyboards.
http://www.musiciansfriend.com/ex/sh...368?pid=425001
It's a "Chord Finder"....... it has three different rows of options that you can scroll through. The first one is all the keys (C, D, E, F, G, B, A and the sharps and flats), the second is the suffix of the chord (M,m,sus,M7,7,m7,etc, etc), and the third is the "tension" of the chord (I don't use this one much, it's used to add things like 6th's, 9th's, 11th's and 13th's........ I think you'd probably use this for jazz styles mostly) But anyway, it's really cool... it's got a little 2 octave (I think, maybe 1 1/2) piano keyboard display on the bottom of the screen. When you enter a chord, it shows you which notes to play for that chord..... it also has inversions and variations. It has another mode that lets you enter notes on the keyboard part, and then it tells you what chord that is...... I don't find that part as useful, but if you're playing something and keep saying "What the heck chord is that?!?".... then you'll find this mode useful. Ok, just thought I'd let y'all know about this cool little toy/tool/reference/etc/etc. And to let y'all know that I recommend it.