I'm not sure if any of you guys here are familiar, but this is a really cool service I've been using for the past 5 months to practice Super Street Fighter II Turbo.http://www.fightcade.com/
The main focus of FightCade is for people to play classic 2D fighting games online, but several other titles are also supported such as Final Fight and Puzzle Bobble. As long as both players have a decent connection, the games run very smoothly.
Have any of you ever tried FightCade? What are your thoughts on it?