Just a quick message, apologies if any of this has been mentioned before.....
I've been hunting around and found "Pocketscumm" which runs old Lucasarts adventure games like "day of the tentacle", "sam and max" (later games "the dig", "full throttle" are close to running well) etc etc
Runs full speed, can even use the full cd/"talkie" game versions
ScumVM site
I also found "Sarien" a Sierra AGI emulator, that happily runs all the older sierra games eg "Kings Quest 1-3", "Space Quest 1-4", "leisure suit larry 1-4?" etc
It also runs quite nicely....though has a little bug and tends to crash if you exist the game from within the game rather than exiting the emulator....
Pocket Sarien download page (pocket atari emulator there too)