Well, I'd also like to fly to Mars. Both events have approximately the same likelihood of happening.
However, if you are determined to track down and capture the elusive agent, Query Tracker is the best place on the net to get the most up-to-date information on agents, plus super search functions to find just the right agent.
Check it out at QueryTracker.net
There is a companion forum filled with writers sharing information, helping each other write the very best query letter possible, and provide support for your sagging ego when you receive rejections like machine gun bullets.
Patrick, the site developer, is a very nice person, too.