This is an offer that has been around for a while, but since I was on the subject of 20,000 AA bonus miles the other day, it seemed appropriate to point out this thread on Flyertalk. The essentials of the deal are as follows:

• 20,000 bonus UA miles after your first purchase
• First year annual fee waived, $60 afterwards
• 1 mile for every $1 spent on purchases
• Free One-way, 1,000 mile, One-class Upgrade Certificate
• $25 United Discount Travel Certificate

The standard deal for this card is 17,500 miles and no waiver of the annual fee at all. So this offer represents a slight premium over that. Where the Flyertalk thread gets more interesting is when the discussion turns towards applying for the card repeatedly in order to accumulate the bonus miles each time. This is actually an approach that works for many cards, though you do run the risk of the card issuers actually enforcing their terms and conditions in which case they reserve the right to deduct the miles from your account.

It’s also important to note that churning through applications isn’t particularly healthy for your credit score. While your score will recover in the long term, if you’re looking for other credit at favorable terms in the near future, it probably isn’t the best idea to be repeatedly making these sorts of applications.