If you're flying to or from Denver this spring, check out Southwest - if you purchase your ticket for January or February (or the first week of March) before 12/12/08, the tickets are half off!
I caught the Buffalo, NY 50% off sale and got $38 tickets each way from and to Denver.
Linky link.
My sister emailed me a similar link with a 'don't you need to come visit me in January?' message :)