TSA publishes average/maximum wait times
 

...broken down by day-of-week, time-of-day, and checkpoint location. Very very handy, and based on my sampling at DTW and SEA, generally accurate.

http://waittime.tsa.dhs.gov/index.html

(Apologies if this has been posted: I tried searching for the link, but didn't turn up any posts, including my own in the Northwest WorldPerks forum...)

IMHO those numbers are very suspect - for example, you are not going to get through Terminal 1 security at LAX in less than 10 minutes! I think the T :mad: S :mad: A :mad: starts counting when you get to the back of their line - if you have to wait an hour to get to that point, they don't count it.

I would recommend checking Airport Wait Times instead, although it may not always apply at airports with different terminals for different airlines.