I like windows media encoder, does a pretty good job, and has alot of options. (you can encode to different bitrates at the same time, for streaming)
Dunno how well WMV9 compares to other codecs tho, but wme is atleast free, and readily available on atleast any windows platform..
Quicktime is pretty good aswell I spose, never cared much for it myself tho..
Xvid or Divx are sorta popular aswell I guess..