Well, as far as Sam and Max and Day of the Tentacle (two incredible games, I might add), you can get a program called ScummVM which is basically an emulator for all the games that used the SCUMM system. Most of the games that LucasArts made in the early-to-mid-90s used this, so it covers most of the sweet point and click adventure games that are quite lacking these days. Monkey Island, anyone?
As for any other OS7 games, I don't know, and I wouldn't mind hearing an answer either. If they were supported in OS9, I know you can get an OS9 emulator called SheepShaver to play them. Other than that, I'd love to hear other people's suggestions