"If renderosity wants to pay for space on my computer then I'll allow cookies from their site. "

That's the silliest thing I've ever heard. In order to post in the forums here you must be a member. In order to log in as a member you must accept the cookie that tells this site who you are, your user name, etc. Same for the marketplace. It's the same cookie and that's all it does - caller ID for the internet. A while back they changed servers around and you had to re-log in if you went from the forums to the marketplace but you only had to do it once. If you haven't been to the marketplace since the change that could be why you are seeing the request.

Anywhere you use your credit card will require a cookie on your system so good luck taking your business elsewhere.

...... Kendra