Anyone play "Realm of the Mad God"? (ROTMG)
It is a perma-death MMORPG. I found it via Chrome store. It is also on Steam, but I find it plays better in Chrome. Flash based.
I really dig this game. It has a lot of interesting ideas and I think it caters to both casual and hardcore players. One of the things I like about it is that it has a button to teleport you to the home sanctuary, so no matter what I am doing I can get up and tend to my wife or kids if they need something right away. It's free to play and you can buy extra bank space or characters. The inventory and trading system is very basic and simple.
I enjoy playing enough on my own and getting achievements, but the game is also very rewarding when you team up with others. When I show it to my friends they immediately start laughing when they see the graphics and basically don't give the game a chance. If you haven't heard of it I recommend you check it out and look through their wiki!