The main page here at Ironworks has a portraits section. You could also try fileplanet.com, they have a lot of them. Last I knew there was a link to a very extensive collection of portraits at Mithril Hall:
http://www.xsorbit.com/users2/Whisper/index.cgi. Ogres and orcs are tough to find. There are a couple half-orcs at this site:
http://gknights.org/dnd.