http://www.arcadetown.com/blackknight/playgame.asp
I've been playing this on another board for the last couple of days, and i can't seem to stop playing it.

My highscore there was somewhat 66.000, but there were people with almost 90.000. Just hit anything you can, and buy better weapons in time, or you wont make the cut.
Have fun, and don't forget to post your highscores.