I like Carl's list, in a cost-is-no-object way. Generally speaking, there is no complete list, given the number of high end headphones, cables, amps and tweaks. Realistically, you need a pair of good, open Senns. Balanced 650s rock, but that works out to major money very quickly (mostly because of the amp). I echo the sentiments about the HD-590s. Even with the stock cable, I cannot believe the soundstage they provide. I heard them described as the "Sennheisers for people who don't like Sennheisers." They're also fairly cheap these days.
If you're looking for more cans on the cheap, add a pair of Koss Porta/SportaPros and try recabling them. It's a very good first-time DIY project, and one that won't send your wallet on a bender.