etheller.com is currently in the middle of changing server technologies... and the Pacman score connector hasn't been written for the new server yet, so this link was taken down. Expect it again soon!
In the mean time, check out Dinodine which has no high score system and can run on any server technology!
Or play pacman anyway without the high score system at this link: pacman.etheller.com
However, please note that while playing these projects, your computer will spam the etheller.com web server with requests for the "collect pellet" sound every time a pellet is collected, because of a bug with the If-Modified-Since HTTP Header that I didn't implement on my web server project when I wrote it two years ago. Etheller.com is running on that class project server, so it has some bugs currently.