One of the mental exercises I've done for years is to take a song, any song, and play it using nearly every style in the keyboard. Sometimes you come up with some really neat sounding tunes merely by changing the style, and also changing the chord progression with some interlopers. It's a lot of fun and it can really make for an interesting performance. One of the best example of this was when I was visiting DNJ one evening in Brick, NJ. He did Happy Birthday as a disco, then switched to Volare using the same style and variation--the crowd loved it!
Gary