http://www.youtube.com/watch?v=QpGuVdcynJA
Maybe a shield texture?
I can make it seamless texture animation too, if needed.
Colors can be changed by 256 sized palet, and it repeats 256 frames.
Animating with graphics cards is quite a job, takes lots of mem, but its possible to fit 128x128 animating texture with 256 frames to 2048x2048 image, so it could be animated by changing the texture coordinates. 16megs mem takes that, if used 32 bits colors (which they only uses atm?).

Full quality version:
http://www.unknown-files.net/spring/379 ... ma_effect/