Does my fixie need a chain tensioner I'm building my own fixie (almost a cliche, sorry) and I debating whether or not to buy chain tensioners.  I will be riding my bike with a fixed gear most of the time.  One of the reasons I ask is because I see a lot of fixies without them.  So I was wondering whether or not I really needed them.  Personal preference is welcome.
You don't need a chain tensioner (by this, you presumably mean something like the Surly Tuggnut and not a pulley which will snap on a fixie). This article from Lennard Zinn (or equivalently, the one he cites from Sheldon Brown) covers how to tension your chain.