Thats what PBBG is, and many of us developers/players work on/play.
Bud (the guy that owns the PBBG I linked to) was trying to define the genre because it’s not quite a MMOG because it’s played in a browser. And this is what he came up with.
If you are unsure of what style of game this describes, its a game played through the browser where after you long off, the game world still exists and so does your character. It is often defined by 1000’s of players playing a game where they interact very much like a MMOG.
If you a player/developer support this project! This is our chance to make it known that we exist. To make our little corner of the net larger, better… and overall, provide a better playing experience to everyone.