I personally like Chaos Pony and WTF @ TFW the most.
Chaos Pony is a podcast about the Order of the Pony, a massive secretive cult that worships a Chaos Pony. Unfortunately the members that run the podcast are incredibly low level members and they don't know anything about the Order, so they mostly just talk about their lives.
WTF @ TFW is a podcast for the TFW2005 forums and talks about transformers news and other things of note. Its particularly good thanks to the energetic host Vangelus, who often gets over excited.