P90X - Almost with a straight face
I'm sure quite a few of the fitness oriented folks around here have at least *heard* of P90X, a Tony Robinsesque "EXXXXTRREEEEMMEE" series of videos. The theory isn't novel: work your ass off and eat better for 90 days and you'll look and feel better when your done.
After sliding downhill for essentially the entirety of 2009, my friend RobD and I are taking the plunge. If anyone feels like joining us, post your pain here.
It's not exactly cheap, but you CAN find the DVDs for about $50 bucks on sale, and the equipment required is quite minimal (a pullup bar and either dumbells or a set of resistance bands).
I'm day 1, and it kicked my ass, but in a good way. The dude is way less annoying than the infomercial stuff you'll see on the web, I actually kind of like him, and not just because he's a bit older and self deprecating.
Nutritionwise, I'm not following the fairly dirt-standard workout diet, rather just falling back on common sense and using livestrong.com's free food counter and 3 dollar iphone app to keep better track of what I'm eating.
I only post this here because I got a lot of twitter DMs when I posted I was starting, so perhaps I can drag some of you out of the woodwork.