There's a one-time tax credit available for people who didn't get a full economic stimulus payment in 2008. If your circumstances have changed making you newly eligible, the recovery rebate credit may be worth pursuing.
The IRS will figure what the credit will be for individual filers or you can do the figuring yourself. Among those who might be eligible are families who had an additional child last year, and people who didn't have a Social Security number in 2007, but obtained one last year.
Unlike the stimulus payments that were made by check or direct deposit, the credit adds to the amount of a tax refund, or decreases the amount of taxes owed. The maximum payment was $600 per taxpayer, or $1,200 for those married filing jointly.