Help with a new TCG (trading card game)

I've grown up playing a lot of table top RPG's including the grand old Magic: The Gathering. I'm working on building a TCG as one of my next games and thought I would come by here and see what sort of things you guys would like to see in one.

A little bit of info to start.

The game will be turn - by - turn multiplayer and built in unity. Apple's Gamecenter doesn't support turn-by-turn and Openfeint doesn't support turn-by-turn in unity, so we are currently working on building our own servers. I know a lot of people don't like having to create new accounts to play games, so I'm talking to electrotank (they make the server software) about easy ways to login and store info. Maybe something like a facebook login or a way to plug into gamecenter accounts. Nothing concrete yet on this.

Steampunk setting. All the card games I've played (MTG, WoW etc) are set in high fantasy. I like that genre but I'd like to switch it up a bit.

Taking advantage of the medium: While the game is a TCG at heart, there are some things we feel are outdated that can changed for the digital medium. When this stuff is more fleshed out I can get into it more.

The game is still early in development but I wanted to see what everyone thinks about card types. I have a list of 300 starter cards and what they do, but it would be fun to get some more ideas from you guys before I started working on art.

So do you have any ideas for card types? You know, things like +3 attack for the next 2 turns. Or, allies on the opponents side are confused for a turn and attack each other.