Playstation network should add Sonic Adventure 2. I had it for the sega dreamcast and I had alot of fun. I haven't tried the version of it on the game cube but i still had enjoyed the missions.
Sorry, but this forum isn't an open ballot. People can ask the PS Store to include X, Y, and Z all they want but nothing's going to happen.
Asking on the SEGA forums would be much better. Also they already confirmed they will release Sonic Adventure 2 Battle on both PSN and Live.
Above you can see where multiple sites have confirmed it.