there was a hiphop thread pretty recently where people mentioned a lot of good stuff.
here:
http://216.70.73.169/gossip/showthread.php?t=968
don't bother with kid koala until you've checked out lots of other hiphop, he's ok but there are plenty of things that are a lot better.
here are my top 11 MCs in no particular order
chuck d
the guru
kool keith
kool g rap
percee p
ghostface
mf doom
gift of gab
nas (but only because of illmatic)
sir menelik
erick sermon
top 11 producers
the bomb squad
dj premier
the rza
dj spinna
pete rock
dj shadow
chief xcel
q-tip
mf doom
el-p
madlib