One of the big disadvantages of the Slant approach is that people don’t get direct feedback for their contributions like you do via upvotes on answers on Stackoverflow.
A lot of the time it feels like you’re contributing into a vacuum and no-one really appreciates your efforts.
@tim has been talking about a thank you system for awhile now, and I think we have an approach to make it work. It would involve grouping the activity on the question page by person, then making it more prominent and then allowing people to thank a contributor for that activity. Something like: