General Sega
Bios Images All system Bios Images are found here
Sega 8 Bit to 32 bit
Kega Fusion Emulator home page Best Megadrive/Genesis plus all ad-ons Emulator (Also covers Sega 8bit consoles)
Gens Emulator home page Next best Megadrive/Genesis emulator, support everything that Fusion supports excluding CD-32X
Sega Mastersystem
Emulators - see Sega 8 Bit to 32 bit
Roms
Sega GameGear
Emulators - see Sega 8 Bit to 32 bit
Roms
Sega Megadrive/Genesis
Emulators - see Sega 8 Bit to 32 bit.
Roms
Genesis Collective Offline Games database, includes reviews/In game cheat codes/Game Genie codes
Codebook Game Genie codes
Sega 32X
Emulators - see Sega 8 Bit to 32 bit.
Roms
Sega/Mega CD
Emulators - see Sega 8 Bit to 32 bit.
SCDToolz 3.55 Organizer for Sega CD dumps
CD Images
Sega/Mega CD-32X
Emulators - see Sega 8 Bit to 32 bit - Fusion only.
Sega Saturn
SSF Emulator compatibility List
SSF Emulator home page Best Saturn Emulator (it's japanese)
SSF Older versions (see Compatibility List for recomended older versions for game X)
Saturn Region Patcher
CD Images
Satourne http://satourne.consollection.com/
Saturnin http://saturnin.consollection.com/
Yabause http://yabause.sourceforge.net/
Other Emulators http://www.zophar.net/saturn.html
Sega Dreamcast
NullDC Emulator home page Fastest Dreamcast Emulator but lacks WinCE support
Demul Emulator home page This emulates some games NullDC does not support including WinCE
NullDC 1.0.4 r141
NullDC 1.0.4 r150
Utopia v1.1 CD Image Boot CD for none Selfboot/Mil-CD games (do not think this can be used with the above emulators though)
Disc Images
As with the others in other sections this is just a start and can be added to