[Twinny]

You could do server-orientated packs of cards. Like buy 8 cards for Zodiac. Cards might include rare weapons, novelty items, stat boosts, temporary effects (like a godmode card that makes you invincible for 15 seconds to NPCs).

If you do packs, don't have a pack with cards for multiple servers as this would not appeal to many people. Keep them server specific.

Only bad thing is that this won't work for every server. For instance, Packs wouldn't work on N-Pulse because there isn't much to get there.

Could also get cards which unlock global games you could play as well as things like a sneak-peak at graal 3d for 5 minutes card.