I could watch 40 Year Old Virgin once a week if I had the time. But here are a few others that make the grade:
Caddy Shack, Ferris Bueller, Animal House, The Jerk, Anchorman, Beerfest, Fast Times @ Ridgemont High, most of the National Lampoon Vacation series, Clerks, most of the Judd Apatow movies, altough I don't know if they'll stand up over time.