Are there any English servers where I can play Mahjong online?
I've played Mahjong online through Yahoo. But, there usually aren't that many players on their server. Yahoo also have solitaire Mahjong games, if that's what you're referring to.

You could also try MahjongExpress. I've never played on there, but it looks like it requires you to install software, kind of like the online poker games.