One tweet. 
Just one. On a Wednesday night : “Dear Twitter network, my office is having a book sale for @UnitedWayTO – Anyone wanting to donate books, DM I’ll pick them up.” 
Within 24 hours, I had three offers and had to stop taking books for fear I couldn’t deliver them to the department taking them or fit them in my Zipcar! Within one week, three people had given me almost 300 books. If I had taken all offers, I would have had more than 1000 books. From one random, undirected tweet. Imagine if there had been real intent or strategy behind that ask? 
For the converted, hey you know the power of social media for philanthropy and social business. Let’s remind the naysayers, it’s time to dip your toe in the water! Create an account, learn the lingo read Unmarketing on why organizations need to invest and for the business set Scott’s new “Book of Business Awesome” will help with that nagging ROI itch too. On that note, it’s not a big deal to anyone but me, but I crossed 2000 followers on Twitter this week – A humble thanks to all of you who read, respond and engage. Thank you for allowing me to be a part of your net
work! And to those three people, I thank you – and the United Way of Toronto thanks you too! I leave you with a little video note from them… Paul
Nicely said, Paul. The thing is, you were providing a service. People with books overflowing want them to go to a good home, and often don't know where to send them. You also offered to pick them up, which made it easy.
PS Great video. I'd love to know more about the artist who designed the three portraits.
I LOVE Twitter! I've connected with so many great people and made such awesome connections via this medium that I now sing the praises in formal presentations about the value of Twitter.
I would say that your call to action worked for two reasongs:
1. You established some great relationship first through engagement and sharing.
2. You selectively make requests of your followers.
Social media is a wonderful medium, but it is one that requires nurturing and the establishment of trust.