Most games have them. All successful games do. The Super-Fan. The 1%ers. The folks that are REALLY, REALLY into it.
Super-Fans build fan sites, some so elaborate they rival (or best) the publisher's site.
Super-Fans participate in on-line forum discussions, chats, and blogs. If the publisher doesn't host such things, the super-fans start their own.
Super-Fans buy EVERYTHING, and often more so their friends (or local deserving kids) can have your game too.
Super-Fans volunteer at conventions and run local events. (If you help them, sometimes even if you don't.)
If your Super-Fan owns a store, it's probably a top seller of your game. (With Clout, the stores where the managers/owners loved the game sold piles of chips. Unfortunately, there weren't near enough of those stores!)
At the Tangled Web, Clout tournaments were huge. The manager was a super-fan.
The key to getting the most out of Super-Fans is to understand why they are Super Fans (beyond you're game being awesome, I mean.) Like most people, they like being a part of something, and you're lucky enough that they chose you're game community to be a part of. What do they want in return?
Stuff? Sure, but not really.
The inside scoop? Hells Yes.
Super-Fans want you to know who they are and they want to be a part of what you're doing.
Everything you can do to make being a super-fan an easier thing to be, will pay dividends. They'll have an awesome time, you'll sell a lot of games. In the game industry it means having communities tools in place. It means having customer service and/or organized play people that communicate two-way. Super-fans put forth extra effort. It's your job to recognize that. Shouting at them through boilerplate, press releases, and ads is NOT communicating. That sort of thing is for the customers, maybe the regular fans, NOT the Super-Fans.
Are Super-Fans worth it? Of course. Even if you're really into the games you're making, they're more into it. With TCG's, the average Super-Fan knows more about the games than the average employee at the company publishing the game (a fact many Super-Fans I've met don't like, but hey, it's their passion vs. our job!)
Also, Super-Fans are awesome to hang around with at conventions!