In addition, two good nationwide sites for races of many different distances are http://www.runningintheusa.com/Race/Default.aspx and http://www.theschedule.com/ (I've used both).
Depending on where you live, there may also be local or regional websites with detailed race listings. For example, here in Southern California we have Raceplace, which covers the entire area from Santa Barbara to San Diego and everything in between, http://www.raceplace.com
"...I've learned that you shouldn't compare yourself to the best others can do, but to the best you can do....I've learned that you can keep going long after you think you can't..." --- author unknown
2013 highlights...
@ 5K:
Ontario Mills 5K, Ontario, CA, 24:42
Heart of the City Run, Los Angeles, CA, 24:13
Downtown Anaheim 5K, Anaheim, CA, 24:32
@ 10K:
LA Chinatown Firecracker 10K, Los Angeles, CA, 51:42
The Great Race - Old Agoura 10K, Agoura Hills, CA, 51:12
Fiesta Days Run, La Canada, CA, 49:31
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