is offering 1500 miles to new members who join by July 31. Just enter promo code NM15 when signing up.US Airways
This might come in handy since US Airways is rumored to be in merger talks with United. If I were you - get as many US Airways miles (shopping/flying/credit cards) and Continental miles (also rumored for merger with United) as possible. That way, when all these accounts are combined you are sitting on one huge mountain of miles.
I did the same when Northwest seemed to be talking to Delta - I got as many Northwest miles as possible - around 70K, when both programs were merged I all of a sudden had almost 200K Delta miles - a small part of that was used to fly to Japan for $40 each. So you see - planning & preparing pays!