Super Sonic fix - Makes Super Sonic's textures always load, preventing crashes when using Cheat Engine or the Trainer.
GC SET files - Object layouts from the GameCube version of SADX, with more background objects than the PC version.
Metal Amy Adventure DX - Replaces Sonic with Metal Amy, who has different abilities than normal. Topic on Sonic Retro forums
Not-so-Super Sonic 2 - A hack with stuff, including Amy Rose. Currently not being worked on.
S2Boost - A Sonic Rush style boost in Sonic 2.
Sonic 2 Secret Rings edition - A hack adding missions similar to Sonic and the Secret Rings. Topic on Sonic Retro forums