Yohoho! Puzzle Pirates, a puzzle-based MMO-Arrr!-PG in a cartoony pirate universe, won the Technical Excellence and Audience Awards in the web/downloadable category at the 2004 Independent Games Festival. Lots of great links to indie games in the winners list.
Puzzle Pirates has been picked up by Ubisoft for distribution in stores. $20 for the box, $10 a month to play. Seems like a lot to pay, but it looks like a great way to introduce MMORPG monthly pay-and-play to a casual gaming audience.
Download it free for Windows, Mac or Linux, and try it free for a month without having to surrender a credit card number.