It would be nice to have moving with relative coordinates as well as absolute.And rotate, yes!
Maybe scale and things too...
Mosaic/wavy/water effect(s) would also be cool but I won't lose any sleep if you shoot that down; I don't know how practical it is. I think OpenGL has API methods for that though?Hmm... H-blank effects? =D?
Adding combination of the "speed up/slow down" effect would also be nice so you can have something start fast, slow down, then speed up again as well as slow, fast, slowSo different forms of interpolation? Right now you can emulate that by using several points where delta time != delta position.