The ads also still get traffic, A while back I wrote a script to list all the domains that had expired and bought one at random for shits and giggles. GA reported about 100 uniques per month.
Hilarious! I just scraped all the domains and did nslookups on all of them to see which where expired. Then I registered the one with the largest area (milliondollarconnect.com occupied 1000 pixels) at x1, y1 = 710, 750 (the ad that looks like a glassy oval). Will report back on traffic.
that's a pretty interesting idea. I did something similar a while back to grab expired image hosting websites that still had a ton of images linked to them.