Certainly a place to find programmers willing to work for a non-profit for a discount would be one thing to offer.
But a lot of grass-roots not for profits, larger ones, at least, also have people they can draw on from the community if they have some idea as to what they want to do. And more importantly can raise grant money for projects if they can clearly articulate what it is they want to do. A resource that gives examples of good non-profit websites and clearly explains how technology like a nearly bug-free (ahem) toolkit like the ACS can be used to build such sites at reasonable cost or with reasonable amounts of skilled volunteer labor would help them tap into both resources.
