I'm trying to go play Streets of Rage and Streets of Rage 2 on my Wii. Both are awesome games, especially for fans of the genre. I found this Streets of Rage Online fansite, and for the last hour I've just been looking through their info. They have all the info.
Also searching around I found some cool fanart. Tons of dedicated Streets of Rage players, and with good reason. Streets of Rage is one of the best Beat 'Em ups of all time and it was released very, very early in the Genesis's life, in 1991. It would beat out Final Fight to the arcade, although it seems likely that somehow one dev team spied early versions of the others's sprites. I don't know for sure who ripped off whom, but both games defined a genre more than Double Dragon and River City Ransom ever did.
Not that the Technos games are bad, and both Final Fight and Streets of Rage rip plenty of things from both games, while introducing the idea of multiple characters instead of RPG stats (later games like The Bouncer would hybridize the two formats, having multiple characters and allowing the player to level them all up).
The Bouncer also included the traditional 1v1 mode that some many games have. I picked up The Combatribes for a few bucks a month ago and it's versus mode is just awful. All the 1v1 modes were total shit.
Back on topic: Streets of Rage kicks ass and the music kicks ass.
Below: fan art.