Emulation

Emulators -
     Gens - Very good genesis megadrive emulator, great speed and sound one of the best
                 - Runs Only Genesis Roms
                 - Download

      Ages - This is the only 32X and Mega CD Emulator I know of. Runs fairly smooth but I cant get sound working.
                 - Runs Genesis, 32X, and Sega CD Roms (I use only for 32X and Sega CD) I would only use this to play Knuckles Chaotix and thats about it!
                 - Download

      Meka - Very good Master System emulator.
                  - Runs Master System and maybe a few gamegear Roms
                  - Download
Roms -
Genesis (MegaDrive) -

      Sonic The Hedgehog - Sonic's first adventure, if your looking for a classic then this is your game!

      Sonic The Hedgehog 2 - Sonic's second game against the evil Dr. Robotnik but this time he has Miles "Tails" Prower to aid him in the quest.

      Sonic The Hedgehog 2 & Knuckles - Play through the levels not as Sonic but as the hard case Knuckles!

      Sonic The Hedgehog 3 - One of the best classic sonic games made, You have the choice to play as Sonic and Tails together, Sonic Alone, or Tails Alone!

      Sonic The Hedgehog 3 & Knuckles - One of the best classic sonic games made, You have the choice to play as Sonic and Tails together, Sonic Alone, Tails Alone, or now Knuckles!

      Sonic & Knuckles - With levels from sonic 3 you can choose to play as either sonic or Knuckles!

      Sonic Crackers - The 4th adventure of Sonic? Well actualy I think its a test version for Knuckles Chaotix, But you might like it!

      Sonic Compilation - A compact version of 3 games put together, Sonic the Hedgehog, Sonic 2 and Dr. Robotnik's Mean Bean Machine

      Sonic Spinball - I dont know about you but I enjoyed playing Pinball in Sonic Adventure 1 but if you liked that then you will like playing the original Pinball game Sonic Spinball!

      Mighty The Armadillo - Play as Knuckles pal Mighty in Sonic the Hedgehog 1

Genesis 32X -
       Knuckles Chaotix - One of the best games Ive played for the 32X you play as Knuckles the Echinda as you and your Pals Espio the chamelion, Might the Armadillo, Vector the Crocodile, Charmy Bee, Heavy the Robot and Bomb the ummm... Bomb! A really great game!

Genesis Sega CD (Mega-CD 1) -
       Sonic CD - Sonic travels to the little planet floating above earth or Mobius im not sure and is there to Rescue Amy the Squirrel I mean Hedgehog (hehe) from Dr. Robots Sinister creation Mecha Sonic! Very VERY Good game... I just wish I could find it!

Sega Master System -
       Sonic Chaos - Much like the gamegear sonics this is actual not all that bad

       Sonic The Hedgehog - Is this the original Sonic before genesis came out? Im not sure but it very well could be! Great game just like the 1st sonic!