I found this while surfing around one night, a rather nifty Java app that generates fractals.  You can vary the color scheme as you like, and for each regeneration you can select an area to "zoom in" on, which then does another round of iterations on the zoomed area.  Theoretically I guess you could "zoom in" indefinitely, but the app only lets you go in ~10 levels.  Still, it's very pretty and is fun to play with.

http://www.softwarefederation.com/fractal.html

You will need Java enabled on your browser to make this work.  If you don't, you can still browse their images gallery.