I like to go to MMA.tv for the latest news on MMA. They have a large member forum where they discuss all different topics relating to MMA and all the different martial arts.
I go to Sherdog.com and MMAWeekly.com to get the latest news.
If I can't watch a particular UFC or fight night... I go to theFightNetwork.com for the event play-by-play.
Another all around site is FightOpinion.com for MMA news beyond just the UFC.
Sherdog.com and FightOpinion.com also have a some really good podcasts which you can get off their sites and off of iTunes.
Here's a pretty good martial arts site that has some MMA content in addition to excellent training advice and tips.