Well, at gog.com there's a list of "games you'd love to see at GOG". Click on
community. All the ones mentioned are already there. You can vote and add new games. You may have to register first, I don't know, I've already bought 3 games.
The top ten "most voted by community" are shown as well. The top four are non-adventures, followed by Secret of Monkey Island (4266 votes), Monkey Island 2 (4060), Curse of MI (3953), Full Throttle (3434), Indiana Jones FoA (2938).
Go vote!