ETF's can be attractive to those looking for low cost, liquid exposure to various markets that might otherwise be out of reach. Unlike in Australia, the ETF market in North America is highly developed.
Some good links for those looking to trade or prepare to trade US listed ETF's below:
AMEX listed ETF's
Eg Real Estate: URE (long), SRS (leveraged short).
Nasdaq listed ETF's
NYSE listed ETF's
Canadian (TSX) listed ETF's
I hope this saves you some trouble when it comes to learning about and trading these funds. There's a lot of risk involved if you don't know what you're doing, hence my research into these products.
If we're lucky, some of the old hands or lurkers on ASF may give us some inside tips on trading ETF's.