Here is how I am working on hand independence, maybe it'll help others. I'll take an MP3 file of a tune that I like and upload it to a program on my PC that will slow down a tune without changing its pitch. Then I can play along with it. For example, I'm using Arthur's tune from his "Laying It Down" CD (highly recommended by the way!) called Boogie Woogie Stomp in the key of C. I find I can keep up by using some left hand bass patterns with the tune at 70% of its original speed. Once I'm comfortable, I'll add some right hand chords, and then later work towards melody improvisation notes. Right now, I'm at the chords level. I find the advantage of doing this is it's not as boring as doing exercises to a metronome, and it gives you the feeling of playing with a band. I know my progress is moving forward faster by doing this method. As I get more comfortable, I can increase the tempo. I'm using a program called the "Amazing Slow Downer" (a reasonable one time purchase price) though I'm sure there are others out there. You can set the file to keep repeating, so I'll sit there and play the song over and over. I discovered this cool method when I played acoustic blues guitar, and now that I've taken up piano, it works well here too!