Mod Rewrite Troubles

[Heliozentric]

I'd like the user to be able to pass a url through in the GET array. Here's what I have so far:

RewriteRule  ^(http:[//]*[a-zA-Z0-9]*\.[a-z]*)/?$ index.php?s=$1 [L]

The problem I'm having is that it will match something like http://google.com but it only passes through as http:/google.com, so it's leaving out one forward slash. Help?

[Heliozentric]

Still can't figure this out. Anyone have any ideas?