Any help is much appreciated. I've included the year I obtained these recordings to try to help narrow it down...

Some smooth house song - recorded off New York city radio in 1992
http://home.comcast.net/~nechrome/smoothhouse.mp3

Very commercial sounding techno track, recorded off Florida radio the summer of 1995 (I'm sure someone knows this one!)
http://home.comcast.net/~nechrome/happytechno.mp3

Classic sounding trance track. Recorded from a friend around 1994.
http://home.comcast.net/~nechrome/trance.mp3

Hardcore track from Base DJ's set at the Limelight, New York city, New Year's Eve 2003.
http://home.comcast.net/~nechrome/limelighthardcore.mp3

I kept the sizes small for easy download, isolating the defining moments of the tracks. But I do have them all in their entireties, so if you think more of them might help, just let me know.

Thanks!

the commercial song sounds 2 unlimited style

the trance song, I have heard that riff somewhere, shame the sample was not the greatest (I know the rules and trying to keep it short).