Gregory's Horror Show - if you love quirky humor, wish Resident Evil is good, and want a tension-induced mental-mindfuck, you can get this game for about $8-14. Also, it's based on a really funny anime involving 2-protagonists trapped in a haunted hotel, who both slowly graduate into insanity. Inspite that description, it's really funny sometimes. And disturbing.
Quest for Glory. I don't see alot of people talk about these games that much, even thought they influenced the RPG genre quite alot, and the wiki is unindepth, shit, and some of the games don't even have image-covers. Basically, a bunch of RPG/Adventure hybrids in which you play as some totally stoned teenager going to various mythology inspired places. First is Germanic, second is Arabian, third is Asian/Egyptian, fourth has a Lovecraftian/Middle Eastern European thing going on, and fifth is Greek. Really good games. 1-4 can be played on DOSBOX, 5 needs a Windows '95/'98 emulator, but I can't find one. The reason why people don't talk about these games alot, I guess, is because they were released during the end of Sierra's "good years", before they started making shitty, cheap knock-offs. Yes, I'm talking to you, King's Quest VII.