eMarketer has a great discussion of what actually motivates individuals to “like” a brand in social nets like Facebook.
#1 for consumer brands, not surprisingly, is an interest in getting information about “deals.”
But the #2 driver is simply self-expression … people simply want to express their support of a company or brand (or nonprofit) to other people. A form of sharing “feel good” news — a fundamental human impulse.
Nonprofits tapping into social nets need to realize that your “friends” do not necessarily crave “interaction” with your organization — check out the list and note that “interact” is firmly entrenched at the bottom.
They do, however, want to identify publicly with you … and that’s plenty to be grateful for.
Indeed, their greater value to your organization might be as missionaries rather than as donors. So be sure you gently offer your “friends” easy ways to take additional supportive steps. As they take those additional steps, they’re probably moving closer to donating (or donating more/again).