In my capacity as a member of the Baltimore County Democratic State Central Committee, I maintain the county party
website in my spare time (and using my very rusty web skills).
Until the start of this year we were averaging about 3-4 volunteer forms a month. Since the primary season got going we started getting about 1 a week. However, once Dean withdrew from the race, we've been getting about 2-3 a day. It seems like former Dean supporters want to do what ever they can to help out (although I have no evidence to support that these volunteers were Dean supporters). Seems like building the parties' activist base will be one of the legacies of the Dean campaign.
Of course this is all anecdotal and could be a coincidence. By the way, if you happen to live in Baltimore County, please head on over to the site and fill out the volunteer form.