I've heard of them, but quite frankly, I think their mission is too narrow. Most of the really poor people in the world ain't Jews, but they deserve clean water, basic sanitation and access to the engines of economic growth just as much as we do. Plus, even in poor countries, the Jews tend to be relatively well-off.
Tell that to the homeless and destitute people who lost everything they had in Gush Katif / Hurricane Katrina.
You could give to Americares, I gave to them after the Tsunami, because I did not know if the Salvation Army had "boots on the ground" in that Muslim part of the world. They are definately non-sectarian, and they were excellent about not asking me for additional donations, I think I got one follow up, and it was not a blatant solicitation.
However, they are a disaster relief outfit, and it seems like you are looking for a long term, non-disaster type organization. There's OXFAM, of course, they are probably pretty lefty, but I never heard anything bad about them. They fight hunger, and they are British, but I'm sure they've gotta a way to accept donations from the US. There's also doctors without borders, I think they are pretty ok too, although I guess the original group was French. And I guess if you wanted to stay with an American based org. there's Habitat for Humanity, don't hold Carter against them!