I got so caught up by "But let justice well up like water, Righteousness like an unfailing stream" (which, sidebar, MLK's "I Have a Dream" speech -- "we will not be satisfied until justice rolls down like waters and righteousness like a mighty stream.") that I forgot to post the other bits that had struck me from the post:
In an especially powerful passage Amos condemns those who wait for Shabbat to end in order to resume corrupt business dealings; that still rings painfully true today.
Amos rails against the nations who behave in immoral ways, and against Israel who behaves in immoral ways. Like Elisha, he's concerned with the treatment of the poor; he knows that mistreatment of the poor is exactly what God does not want. One of the major messages I take away from Amos is that being "chosen" by God does not let us off the hook.
Indeed: being chosen puts us in an even more difficult position. "You only have I known / of all the families of the earth" -- we are the people God knows, so we're the people God gets most angry with for failing to live up to who we could be.