On cams joining fan club - Gives you special discounts for specific hosts and their online content, on Live Jasmin this is simply called Sale and means you'll only be paying $0.98 credits per minute and there are several more.
Look for these types of promotions because they mean you get to chat for less.
On Cam Soda users receive 200 FREE Credits when they sign up.
These are actually free credits, but since this is one of the few web cam sites that still charges for membership, let's call it a bonus.
For example: The people at bongacams grant you 5 Tokens bonus on your first purchase.