The Kingdom of Loathing
Wonderfully silly writing and cleverly designed quests make this an exceptionally fun and addictive RPG. (And don't forget the cutting-edge graphics -- tee hee.) You could easily play all day, but luckily, you can't; finite daily adventures ensure that you won't miss too much of your life in the course of saving the Kingdom.

The Caverns of Hammerfest
The perfect arcade game for a casual player. Charming graphics and flawless controls make this a joy to play, while dozens of quests and hundreds of items make you want to play again... and again... and... Well, watching your collection grow from day to day is quite addictive, but fortunately this is another game with limited turns. On an unrelated note, if you decide to try it out and feel like giving me a referral, my player name is Vanilleon. ;)

Jay Is Games
Feeling cheated because there are only three links on this page? Well, lament no more! Here you can find arcade games, puzzle games, physics games, room escape games, platformers, shooters, woofers, tweeters, interactive fiction, and a few games that defy description... nearly all of which you can play for free, right in your very own browser. Aside from cataloguing more games than you can shake a stick at, the site also provides copious hints (and often full walkthroughs) for every game it features. Now that's service.