A free-to-download, free-to-play online action RPG, Dungeon Runners is apparently for Windows machines, though it doesn't say that anywhere on the web site.
A free MMORPG superificially similar to Heroes of Might and Magic, "Myth War" is free but is not a web-based game in the strict sense, as it requires a local client to play.
1UP.com yanked the original review for Neverwinter Nights 2, which is reprinted in Joystiq's web journal entry. The original rated the game 5/10; the new review rates the game as 6/10.
Excerpt:
Jade Empire finally came to PC earlier this year (2007) after being released for two years on X-Box (2005). Unlike other console to PC ports, Jade empire plays smoothly and the controls feel natural. The story is based in a fantastic and mythical China (called the Jade Empire in the game) and the fighting and many elements of the game borrow heavily from the wuxia (pronounced wu-sha) genre of movies, books, and theater. As an action-role playing game based around martial arts and magic, the environment is unique and compelling - I know I couldn't stop playing until I finished the game.