A whopping 19 active campaigns on visitbit at time of writing
Although, some of them are all referral links on sites which don't allow frames! Folks, if you're going to use a ref link to advertise, please ensure the site allows framing.
Now, another nice little update for advertisers.UPDATE
You can now choose traffic sources for your ad. It costs an extra 0.001 BTC on top of your bill, but you'll be able to whitelist the country of origin of your visitors. See: http://visitbit.com/advertise
You'll notice a checkbox now labelled: "Limit Traffic Sources?"
If you check the box, you should see a text box appear.
Start typing the name of the country you want to accept traffic from, and click on it in the list. You can add as many countries as you like this way.