Suggestion - Badges
As Mark2Cure releases more campaigns and gets a steady group of long-term users, I think it would be neat to have badges on our profile page to show which campaign each user has helped on. Each campaign could have it's own little badge and then inside the badge might be a percentage or specific color to show how many quests (or points) were completed for that disease.
I'm actually stealing this idea directly from IBM's World Community Grid which does something very similar. It's a great way to feel accomplished and see which causes you've contributed to over time.