I've seen a few posted here, but I'd just like to ask anybody to list some recommendable Persistent Browser Based Games.
They seem to be growing in popularity, I see a banner ad for a new one almost everywhere I go online lately.
The only one I've played is Cantr II and I totally loved it (similar to Wurm-Online in your browser). It has a huge persistant world where everything is hand-crafted by real players. There are no NPC's, besides animals for hunting and players are required to band together in clans or villages to survive. Discussing tips, maps and events out of the game is prohibited so the game has an almost "Myst"-like quality to discovery. You will find projects, journals and maps of the deceased and can continue the work that they began.
An example of a typical in-game event could be to discover a cabin in the wilderness where it's last owner's remains are strewn about. Finding their journal you discover that they gave into starvation and lion attacks. Using their gathered resources you can continue to build their house and continue the work they began.
There are only a couple things that bothered me about this game. It is played in real time, so travelling from one village to the next can literally take several real-world days (your character continues to walk when you're logged out). It's a cool concept, but gets dreadfully boring at times.
Also, magic and magical creatures do not exist. I think it would be a little more fun to be able to slay monsters and acquire magical equipment.