Newsbusters looks for left bias and Mediamatters looks for right bias. There's a lot of petty stuff in both, but personally, I find Newsbusters has more substance in their gripes than Mediamatters and they definitely have more volume.
As to the network news, my TV has rabbit ears such that I watch MSNBC most of the time. FOX is fuzzy and not worth the bother. This may change February when I'll be forced to upgrade my reception capabilities.