Though Sharebuilder may not be my preferred brokerage (Sogo Invest is for their $1 trades for the first 90 days and $3 thereafter), they are the only ones offering a sweet deal like $50 cash for opening up an account. To obtain the money, you only need to make one trade, for any value, and they will deposit the cash into your account in a few weeks. The good guys over at Blueprint for Financial Prosperity detail it extensively and list quite a few codes. http://www.bargaineering.com/articles/sharebuilder-50-bonus-revisit.html

I went directly through the Costco website (you do need to be a member), but I have received notification that my cash ($55) should be coming in a few weeks. It's a GREAT way to invest in something risky, for which you wouldn't necessarily wouldn't want to put your own hard-earned dough on the line.

Another benenfit is that Sharebuilder is available in Yodlee.