Slice,
I have only done a few credit card offers and I will only do them if I probably would have tried the product anyway. I did the Gevalia and Blockbuster, but I still have both of them because I like them. I would caution you against doing a CC offer with the express intent to cancel because you could easily have the credit revoked later since that is against the rules.
Regarding new offers, I understand exactly what you are saying because I couldn't figure that out either. I was used to sites that add offers daily. Different sites are better for different things. Although FC does not get new offers constantly, if you will do the .15 daily and throw in a survey here and there you can probably cash out every other month. If you get referrals and they complete an offer you get $3. So if you are good enough at getting referrals, it adds up quick. Right now I still do more surveys than I like because my goal is to be able to cash out each month with at least $25. Since I am getting a few referrals, but not a lot yet, I have to put in a little more effort.
If you get referrals to try a few offers here, they will see that they approve really easy compared to other sites. I was amazed when I started here because it seemed like everything was approving. Then they cash out and you get another $5.
That is the best way to use this site. Keep telling more people. If they put in much effort, they will be able to cash out the first month and put $8 in your pocket too. Eventually you should be able to just do the .15 offer and a couple surveys and get a very nice check every few months. Very little work for the pay, really. It just takes a little effort in the beginning.
Other sites do have many offers, but my ultimate goal is to spend more time promoting and less time completing offers.