Do you know what would I do if I had an LL like Link-o-rama for instance. I'd build my own VIP area where I'd push HQ sites for $1 monthly, just to distinct payable surfers from the other punks out there and build some better marketing knowing that you're not serving SEs, nor other LLs - you'll be building a site only for your VIP members - not so many restrictions that you should care about. The advantages of such VIP area are actually pretty much, you should think about it
I think this could be done with you current LL software by only adding a new category and restricting access with .htaccess and offer signup on an unsuccessfull login.
Since this is my *reply* I would appreciate if somebody let me know if he/she decides to do it any time soon
