I always thought the angled sprites (for example, the right sprite) for when Sonic would walk/run through a 360Â° loop were done by simply rotating the regular walking/running sprites (for example, the left sprite) at a 215Â° angle but ultimately found out (through a project I'm doing) that it wasn't the case. Unless what I'm saying is not true, then I should find out in that case what kind of programs are out there that can do a really good job of rotating graphics at any angle.[/quote]
Good luck finding them because there's no such thing unless you like anti-aliasing. You're going to have to rotate them yourself, and then fix up any of the mess that was caused in the process.
You can get pretty close with the right programs though. For example (I used lots of sprites from your spritesheet because it was within easy reach)