The Starwood Amex card has the first year free with 4,000 miles on first purchase. Also, if you do a search, there had been a UA VISA card with first year free which gave 15,000 miles on first purchase. You can find details of most of the credit card offers in MilesBuzz.

One issue you need to look at is the credit limit and the maximum number of miles/ points that can be awarded each month.