something I tried. seen if I can get something that looks good, well it doesn't look that realistic but it is kind of cool to watch.
if I spend more time on it I could get it to look good but I have other more pressing things.

http://www.blackwyrmlair.net/~sk/lava.avi

Looks great! Would the same texture/material work on this shape lava?

http://www.duck.dk/cgi/jussing_lava_animation_web.mov

thanks, yep should work on any model.
I dont think I kept it tho.
I started with a cellular texture then in the 3 mapping channels I added noise maps to each, to them, black red, orange red, yellow white, then added the keyframes and adjusted the spread? to get the swell effect and adjusted the Z position along with.