Got the following email from TD Ameritrade today. I am already an account holder with them:
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Wouldn't you love a chance to get away? You deserve it! Now you can make it happen – and do something for your future investment goals at the same time.

By consolidating your investments, you're putting the power of TD AMERITRADE behind even more of your money. Don't forget that you get long-term support from us as well as objective third-party research, innovative trading tools, straightforward pricing and more.

This offer only lasts until September 30

So make a deposit or transfer stocks, mutual funds or other investments from another broker today. We'll handle the rest – you don't even need to write a check! Get started.

Deposit or transfer $300,000 Earn 75,000 AA miles
Deposit or transfer $150,000 Earn 50,000 AA miles
Deposit or transfer $50,000 Earn 25,000 AA miles

Have questions?
Call us! Our TD AMERITRADE Client Services representatives are available 24 hours a day, seven days a week at 800-669-3900.

And here is the relevant fine print:
1. Offer valid for pre-selected clients who respond online to the offer and complete a qualifying deposit or external transfer into a new or an existing (non-IRA) Individual or Joint account by 09/30/2010. Offers are not transferable and not valid for IRAs and other tax-exempt accounts, Amerivest-related accounts, TD AMERITRADE Institutional accounts, internal transfers or with other offers. Limit one offer per promotion. Account must remain open with minimum required funding for 12 months, or TD AMERITRADE may charge the account for the cost of the miles. Please allow 6 weeks from account funding for miles to appear in the AAdvantage account.