You got a bike you want to switch to a singlespeed but don’t know where to start? For $21 you can get a Gusset conversion kit from JensonUSA. It looks like this is all you need to do the conversion on your rear hub. Obviously it would save weight to do it the “right” way, but it will save you dollars to do it this way.

Also available is the Surly Singleator…

If you’re trying to convert any recent model bike into a singlespeed, you’ve probably realized by now that since the dropouts are vertical, there isn’t any way to properly tension the chain. Surly comes to the rescue with the Singleator. This handy device mounts to the derailleur hanger and provides proper chain tension in a simple, lightweight package.