I have a DNN 7.02 site. I would like visitors to my site to sign up for the two clubs I offer. Birthday club and Rum cake Club. So, I can send them special coupons when it's their birthday. Also, for those in the rum cake club I will allow them to receive alcohol (Rum) cakes. I'm guessing I could leverage the newsletter module? is that the best way?

Yes, that would be a reasonable thing to do.

You might, though, want to consider automating the birthday emails. I found that the Cross Bulk Mailer module does handle birthday emails. There may be others.