Anyway, it looks like Bitcointalk is still a great place to run ad campaign. Based on this discussion currently there's 32 active signature campaign paying bitcoins (if I'm not mistaken). I can't imagine there are many online gambling casino companies doing this sort of thing. Hopefully, this will last for a long period of time just like many others.
There are 28 active ones as per the Overview thread.
Are you guys aware of any other forum in the world that would have similar campaigns?
It's pretty crazy to think that there are people from poor countries making their living just by posting on bitcointalk. The highest-paid campaign currently pays $6/post, which converts to around $910/month. Not enough to survive in "the West" but there are plenty of countries you could live a comfy life with that kind of money.
Since it is a win win situation then I see no problems with that personally. To answer your question, there is (or there was since I am not sure if they continue to do it) some forums that do the same thing with a lower payments mostly. Honestly I don't recall since it has been a long time, the last one I remember is an ex signature campaign that opened up a forums with low payment per post.
For the money, it depends from the country you live on it but certainly in western one the payment won't make a living, maybe to buy additional stuff with it at best.