Evan Williams (CEO of Twitter) and Biz Stone (Co-Founder of Twitter) are giving you a chance to feature your Twitter usage on their very own website called Hope140. Room to Read, Charity Water and Global Citizen Year are already there to show you that you can join this great hub of case studies, so if you have experience with good Twitter usage for your campaigns, do contact them.
I am confident to say that the website will become rather popular, as its creators have great on-line networks.
It's really interesting to see this commercial company stepping in to support 3rd sector activity. This idea itself shows the lack of charities in social media sphere, as well as the trend to provide the bridge between more traditional sector and really innovative technology.
I suggest keeping and eye on it time to time to learn and to get inspired;) And of course getting involved!;)