Which companies seem to offer the most promos on your credit reports? For me there are many by Capital One, Providian, and Discover.
I guess if you are really bothered by "junk mail" it might be beneficial to opt out. Personally I like getting offers and choosing for myself which, if any, I want to pursue. I really dont might things by mail at all, I really enjoy getting catalogs and various offers. I can't stand when they try to sell things by phone. By mail you can choose in a second or two if you;re interested, by phone you have to deal with too many pushy jerks.