There is a current diary titled Graph of who's who in donations under $200.00 that provides a partial summary of where the small money is going in the presidential race. The author of that diary suggested that if we didn't think the article was comprehensive we should write our own, so that's what I'm doing. (Note that the graph and the accompanying article are from the New York Times.)
The two major problems I found with the linked diary are that it doesn't include the entire graph, and in particular omits Hillary Clinton from the comparison, and that it was completely unclear if the percentages were of counts of donors or amount of money donated. Those two numbers can be wildly divergent in this case so the clarity matters.
Full graph of small donations as percentage of total amount raised
So, among candidates for the Democrat race, we see that Hillary and Martin O'Malley are both at under 20% of donations from small donors, and Martin O'Malley is barely registering in total dollars as well. Looking at gross dollar amounts, my quick calculation shows that Bernie has raised nearly $11 million from his small donors while Hillary's smaller percentage of a larger number leads to $8.5 million.
I'm not actually trying to draw any conclusions about what this means in the overall picture, but I thought the original diary had enough problems that it was worth writing this one.