Despite being borderline awful (with a few admittedly funny bits from Craig Robinson), Hot Tub Time Machine performed well enough on "home video" that MGM is considering producing a sequel. Right now, talks are extremely early (so there's not a 100% chance this will even make it) with Craig Robinson, Rob Corddry, and that one kid who isn't funny in talks to reprise their roles. John Cusack hasn't been approached yet, because well, he's John Cusack.
You see everyone, DVD sales DO make a difference. On that note, have you bought Dredd yet? Because if there's something I want a sequel to, it's that badass movie instead of this. And Dredd definitely needs to make money somehow.