Well, I think it could depend on what the 'action' is:
- Perform an action and first 100 will get 0.0002BTC for free to our service account
If the action is to make a post on your thread, then no, that wouldn't be allowed, but there are plenty of 'legit' ways you can offer such payment for performing certain actions. Check the Bounties section for examples and to see what usually goes on there.