The KMC 710 "Kool" chain.  A super heavy duty chain from KMC.  These were designed for the abuse of freestyle BMX riding and will hold up to just about anything you can do to them on a fixed gear.  If you want an extra strong, very durable chain get the 710.  Also available in an SL version with drilled plates and an SL Gold version with an additional Ti-Nitride coating.  

Standard version is silver and black.

SL has a silver finish

SL Gold is, well, gold