Webplayer and large content files

I’m wondering if there is a way i can have my users download the content of my game but still use the webplayer a browser to play the game?

I want to do this because i expect the game to be about 500megs and there is no real way to break it up. Even if there is a way to break up the files into smaller pieces, i dont want the players to have to continuously download the same content every time they want to play.

I’d like to achieve something similar to Quakelive

any ideas?
thanks

any ideas?

Why do you need to run it in a browser?