I like the Belkin model I have. I taped it under my desk so it's out of sight and I can use the two ports that are normally upward facing without having to crawl behind my imac.
This one works great. Its powered, has 7 ports (there's also a 4 port version), looks great by itself and can be taped to the back of the iMac - it even comes with the adhesive for that. Can't recommend it enough.