I have been going through a bit of a point and click adventure frenzy over the last couple of days, primarily due to the likes of Space Quest I and II, Police Quest, Leisure Suit Larry in the land of the lounge lizards and Black Cauldron being available at: http://sarien.net/
The site is created by Martin Kool, who has set about making classic Sierra adventure games multiplayer!
You can play the games as you would normally, but other players can also play at same time allowing you to see and speak to each other when you are in the same location. In theory this would allow you to ask for help or converse with your fellow gamers, in reality it means players typing insults and gibberish. Luckily there is an option to turn off the multiplayer.
The games don't currently have a save option and are not guaranteed to be glitch free, but I would certainly recommend checking them out even if it's just to get a retro fix for the day. I would be interested to see if the idea of multiplayer point and click games could be taken further with events effecting all players simultaneously, or with players having to collaborate in order to solve puzzles. As a concept it would be interesting to see developed, although how practical it would be to implement is another matter. In the mean time http://sarien.net/ serves as a nice reminder of some great point and click adventure games!