Just to toss out there, I’ve been thinking about changes in the volunteer sphere over time. Back in the ’70s when I started work in this field, there seemed to be a core of what I’d now call "traditional volunteers," people (most often women) who adopted a cause and an organization and then proceeded to dedicate many hours over many years to their work. They patiently started at the grass-roots and worked their way up committee-by-committee to leadership positions.
About 10 years ago we began to use the term "episodic volunteers," people who tended to be interested in shorter-term involvements and who might have several volunteer activities with different causes. This seemed to be accompanied by some dimunition in the number of single-purpose volunteers.
Now we’re hearing about "unaffiliated volunteers" (and, I’d wager, unaffiliated donors), people who aren’t interesed in long term commitments to a single cause or organization. They seem to exist as potential actors who become involved when there’s a precipitating event like last year’s tsunami and hurricanes. They respond with donations and sometimes with active involvement when moved by events.
Seems to call for different organizing and communication principles than we’ve used in the past.