Ha, my old FLP (when I was a new member in like 200 did that -- proxied Gaia, but just copied the login information that was submitted.

It's a pretty good idea, but I doubt you'll find a dedicated host for it. Although at the same time, you don't need a dedicated IP, unless you are intending on fucking with people's DNS caches. Which I assume then that you are. I'd suggest alternatively a proxy that logs logins; that is spammable to any free host and wouldn't require any client-side execution to modify anything like DNS caches.