There was a recent
thread in the PC game forum on this topic. But I guess it's not like anyone goes there.
Anyway. There's the
fan-made remake of King's Quest 2 done by Anonymous Game Developers Interactive. Pure awesomeness. Much better than the original, even. They're making a Quest For Glory 2 remake, and hopefully it'll be just as good or better.
5 Days a Stranger and its sequel
7 Days a Skeptic. Both decent horror/adventure games for people who loved adventure games when they were in their prime.
Demo World: The Legend Continues is absolutely
required playing for anyone who's a fan of Mario games, particularly Super Mario World. It's like a combination of Super Mario World and Mario All-Stars, but it's a
completely new game. Not only is it pretty long (the all-levels
speed run clocks in at over two hours), it has a bunch of new items and features, bizarre levels and obscure secrets that honestly make you WORK to find them, and it's about 50 times harder than Super Mario World. Highly recommended.
Jam it back in, in the dark.