UltraMarathonRunning.com
Great resource for all things ultramarathon related, the best place to check for upcoming ultras
http://www.ultramarathonrunning.com/
Strava
Upload your GPS data to log your running exploits, share them with other members and participate in Strava challenges.
http://www.strava.com
parkrun
Where my obsession began. Free weekly 5km events.
http://www.parkrun.org.uk/
The Rich Roll Podcast
Good quality podcasts from inspirational vegan ultra-athlete Rich Roll
http://www.richroll.com/category/podcast/