If you just want a decent sampler of what's out there, pick up the "Amores Perros" soundtrack. No Amigos Invisibles (I think), but a lot of other pop people are represented. [/B]
I had the "Amores Perros" soundtrack. It was among a group of CDs I recently sold. For my taste that music was just too raw and heavy, except for a few notable exceptions. If I'm not mistaken, a very popular group from Colombia appear on that CD, Aterciopelados. Seems like I liked their song.
But like you, I don't think Amigos Invisibles did contribute to the soundtrack.
You mention Daniela Mercury. I really like her work. Another cool Brazilian album is Bebel Gilberto's "Remixes." I was fooling around on Amazon.com the other day listening to sound bites and was amazed to see how much Brazilian electronica and techno dance (or trance or ambient or a fusion of all of those) the country is producing...really appealing sounds...way better than a lot of the claptrap I hear on radio here.