DosBox perhaps, but it's MUCH easier with ScummVM.

Apps? ScummVM runs only games to the best of my knowledge, and there's a list in the wiki. Look here:
http://wiki.scummvm.org/index.php/Category:Games

Edit:
Also, ScummVM (at least the Windows version) supports Space Quest
http://wiki.scummvm.org/index.php/Space_Quest

Nope, just CFW 3.80 M33-5. FWIW I placed the ScummVM folder into the PSP\GAME150 folder.

Actually, 3.80 is fine, at least in my case.

Works perfectly on my Slim & Lite PSP with CFW 3.80 M33-5

I've browsed around the forum and saw a couple of issues with 0.9.1. I'll try upgrading now. Edit: Even worse. Everytime I start a game the phone reboots. I've also tried it with the Monkey Island demo, same deal. One thing though, when I first started a game I got a question if I wiant to use stere...

I've just installed the v2 port of ScummVM onto my Nokia 6630. I tried it with Monkey Island and its sequel. They both work, however, there isn't any sounds. According to the wiki, the only files that are needed are those .001 and .002 ones. What am I doing wrong? For what it's worth, I'm using vers...