Just thought I'd add an IP here as it wasn't in the list previously posted by dhicks.
204.197.192.194
CIPAFilter also lists a set of subnets that should be unblocked from transparent proxies, but I think allowing 4095 IP's through your filter for 1 app is kind of ludicrous.
Anyways, thank you to everyone who posts on this forum, it sure as heck makes my job easier.