Petition to UN Secretary General Ban Ki-Moon: Free Burma's Pro-Democracy Prisoners. I support all campaigns for human rights in Burma as much as my energy levels/spoons will allow; which unfortunately is not all that much.
Petition to Pope Benedict: Help Us Prevent AIDS. I had been going to write a rant about the Pope and why I personally think he's wrong, but I haven't found the energy yet.
One of the things I like about Avaaz.org is that once you've signed up, signing a petition is as easy as entering your email address and clicking "SEND". It takes roughly 10 seconds, which is great for those of us who care a lot but have little energy or time. A second thing I like is that the regular emails they send you about new petitions include a large number of internet links, so you can check what they say against relatively unbiased sources such as the United Nations, the World Health Organisation, Red Cross, Human Rights Watch, Amnesty International etc., as well as reports from the New York Times, BBC News, The Guardian, the Washington Post, CNN etc.
I'm not sure I want to spam you by posting the full text of the emails here, but I can forward them to anyone who desperately wants the links (email my livejournal address).