Cruising Howard Dean's wikipedia page earlier looking for confirmation that his candidacy raised $50M (it did!) and I found this nugget:

While presidential campaigns have traditionally obtained finance by tapping wealthy, established political donors, Dean's funds came largely in small donations over the Internet; the average overall donation size was just under $80. This method of fundraising offered several important advantages over traditional fundraising, in addition to the inherent media interest in what was then a novelty. First, raising money on the Internet was relatively inexpensive, compared to conventional methods such as events, telemarketing, and direct mail campaigns. Secondly, as donors on average contributed far less than the legal limit ($2,000 per individual), the campaign could continue to resolicit them throughout the election season.

Open for discussion is why you think the Republican Presidential candidates have yet to tap this same cadre of donors? Surely, we're out here.