After tinkering a little with Gradient Designer and realising I just couldn't figure out what it was doing with the different blend modes I searched on XOR pen and came up with an even better freeware (perhaps) or at least more usable for me in that it has tutorials so I can start to figure out what to do. It seems to allow for a lot of functions within the software including filters and sinewaves of different frequencies.

It's called sTile at

http://www.harmware.net/index.htm

They're not animators obviously so I'm not sure how well they'd work for your purpose, I'm not an animator either (yet, who knows, Carrara may change that ;) but thought I'd pass it over on the offchance it might have some use to somebody.  It's certainly entertained me for the last hour or two :D