Racing
If you like to drive then there are two options for racing.. Collegiate & USAC racing at Fort Leisure and the Dawn til Dusk 12 hr MTB race in New Mexico.

For all
However for those with no passion for racing there is 2009 Artcrank. This event was recently in Minneapolis which a few bloggers covered.

For Fun
4th annual Easter Feaster Billion Bunny Bike Ride April 12 at Martin Park in Boulder