DAK if there is an online resource that lists airlines (long haul only if it helps) that allow you to select your seat when you book?

I know of some - American, North Western, Alaskan, Aer Lingus - that do, and some - Iberia, Aerolineas Argentinas, BA - that don't.

What I'm looking for is flights to South America (Chile or Argentina) where I can specify (with a good chance of getting) a designated seat when booking. AA via the USA looks like one option - are there others?