Norwich Parkrun.
5k Sat. 9 am race; maybe my first one ever?
Very convenient walk to the start and then just a friendly run with 400 other willing souls. A GREAT concept, a free weekly timed run in a park and a good way of collecting stats that lets one get a weekly snapshot of their fitness level (note the similarities to AP).
Some historical details can be found at:
http://en.wikipedia.org/wiki/Parkrun and a bit more writeup on O Joy's posting.
It is surprising that there seem to only be 3 Parkruns in the US currently. While I think that the weekly-ness of these races is probably a big appeal, it seems that well-located US Parkruns would provide a good alternative to the more expensive 5k races.
Aidan had a very good run (21:23). He was staring me down for the whole race, good thing I didn't slow down. We both think we can trim this back a bit.