ScummVM is a great option, as you can download several games (including Beneath A Steel Sky and Flight of the Amazon Queen) free with the emulation software. I've got an HTC Evo and both those games played nicely on it. Lure of the Temptress was less successful as the controls are very fiddly. I've got a couple of other compatible games that I'm going to try out on the phone -- Full Throttle, Broken Sword, and the Monkey Island games.
A couple of new point-n-click games that I enjoyed are The Secret of Grisly Manor and The Lost City, both 99c in the Play store.
There are some great flash games around - check out the Submachine games, which you can play in your browser. They were a bit too big to play satisfactorily on a phone, but they'd be fine on a tablet.