Emulation is amazing. Most of us have probably experienced the joy of such things, whether it be downloading a ton of games you'll never play just because you want to say you have them, or reliving a classic game that stopped working on your old Nintendo systems long ago. Heck, even downloading Japanese titles just to check out what you're missing (assuming you're not living in Japan). It bears repeating: emulation is amazing. The downloadable titles coming out on all the systems and the classic library found on the Wii are sorts of emulation, but you've got to pay. Paying is lame! Sometimes. Here's a solution for some of your emulation desires.
Over at the psp-spot.com forums, there has been posted a thread about the new SCUMMVM v.0.9.1 binary -- a way to emulate SCUMM and non-SCUMM games on Linux, which you should install on your PS3 as soon as you can! SCUMM games include many of the Lucas Arts titles, like Monkey Island and Day of the Tentacle. It's still under heavy development and a few bugs have been reported, so download it at your own risk.