Depends, if you want the regular club stuff there is lots of it, but I don't really care much for it.
As far as good techno in general goes, some of the more mainstream groups/artists to start off with are:
Crystal Method
Ayla
Fluke
Moby
Underworld
If you like that stuff you might start listening to the various genre's of techno (house, hard house, progressive house, trance, jungle, drum & bass, uk garage, florida beats, the list goes on)
As for hiphop...How about some of these...
Arrested Development - upbeat funk with sort of a socio-political bent
De La Soul - definitive alternative rap
The Roots - traditional jazzy and highly skilled instumentation
Digable Planets - mellow rhymes set to cool jazz loops
A Tribe Called Quest - one of the jazz-rap fusion pioneers
Blackalicious - awesome lyrical skills and equally good beats.
Jurassic 5 - sort of a new-school meets old-school type of thing. they put down some sweet vocal harmonies and have 2 of the best DJs in the biz.
Want some 80s? Boy....they had some good guitarists back then.
Queensryche, Iron Maide, Good Metallica, DK, BR, AC/DC, GnR, Queen, Pink Floyd (a 70s band, but they still put out stuff in the 80s). The list goes on...
When nothing then go to
GOTO %GOOGLE%
INPUT "TOP 100 SONGS"
ENTER
OUTPUT="LIST OF POPULAR SONGS"
If i recall more, i will keep posting....