Man I love Abandonware. Ever since I got Dosbox running nicely on my computer I've been able to play so many classic games. Way back in the day when plot, innovation and depth were more important than realistic graphics programmers slaved over hot computers making masterpieces. If you're ever bored and have no idea what to spend all that ample free-time on, check out this site and possibly go grab DosBox yourself (google it). I'd recommend Settlers II and Gladiator as pretty awesome starting points if you don't have any game titles to go by.

Also, if you know any great games you remember playing as a kid and you think they'll be up there, please tell me, it's hard to wade through so many games and find ones I'm willing to play.