From the New York Times:

Just moments before he arrived, Senator Barack Obama had said goodbye to a less exclusive crowd of 10,000 that had gathered to hear him speak across the bay in Oakland. They paid nothing to hear him, but spent $40,000 on Obama T-shirts, baseball caps, buttons and other knickknacks. And the Obama campaign registered each of the purchasers as one of the record 258,000 contributors it signed up in the first six months of the year.

Since he got into the race, Mr. Obama has hopscotched from big-ticket to big-crowd events across the country, trying to turn the early excitement about his candidacy into campaign cash and a national political organization.

Like other candidates, he has worked hard to cultivate a network of bundlers, who can solicit the checks from individual donors for the legal maximum of $2,300 that are the mainstay of any major campaign. But to capitalize on his celebrity, Mr. Obama’s campaign has also employed novel tactics — like counting sales of $5 speech tickets or $4.50 Obama key chains as individual contributions — to pump up his numbers and transform grass-roots enthusiasm into more useful forms of support. No other campaign is known to have listed paraphernalia sales as donations.