ExpertFlyer, continental.com and nwa.com are all great sources for availability information. I've never not had luck finding at least something that is an option, though the routing can be zany. To get to Europe try routing on AF through Montreal, they almost always have seats open on those flights, and CO usually has good availability to LGW. Also, the new Delta flights such as JFK-DUB and ATL-NCE seem to be pretty open next summer. One caveat about DUB, if you connect there, no matter where you are going, you must clear Irish immigration, doesn't take long, but can be a hassle.