I like this.
Bullying.co.uk are running a clever discussion on Twitter designed to raise attention on the issue of bullying.
It is a clever campaign because it reaches audiences (like me) who are likely to miss TV campaigns and not respond to posters. It is also a clever campaign because it appropriately introduces itself to the conversations already going on in twitter - it lets users opt in and support a good cause. If it was always as easy as adding a hashtag to a tweet to support a charity then the world would be a better place.
Bullying.co.uk have combined this campaign with some Google PPC too. I needed to re-install Twhirl to my main laptop after a death-by-adware encounter and Bullying had the keyword targeted.