I remember this game!
A Boy and his Blob! You feed the Blob jelly beans and he changes into stuff! You have to fight evil aliens! I really like the idea of platforming on a bouncy ball and exploring neat and weird terrains. It looks like some talented artists are working on a new version of it for Wii, and its darn cute, but also looks like fun , hmmm. Maybe I'll ask for it for Christmas. Anyways, here's the source and also if you want a link to a fun boy and his blob remix!