Ten23 is a new campaign in the UK working to raise awareness of homoeopathic products, firstly that they don't work and secondly how they waste time, money and can prevent people seeking genuine medical advice when they should.
I won't go through the reasons that homoeopathy doesn't work, there's a wonderful explanation here so go read it. Simply put it's water. You spend a lot of money for a bottle of water.
Ten23 work to raise public awareness that it doesn't work and is a waste of money, they have an open letter to boots asking them to remove homoeopathic "treatments" from their shelves as they are a trusted pharmacist that many will go to as a first line of treatment, using homoeopathic remedies can put these people at risk and they will likely assume that boots, being a trusted party, will have their best interests at heart: stocking only treatments that work.
Talking of worthwhile campaigns this is another: Libel reform which is working to revise the libel laws in the UK. To reduce their cost and make them less plaintiff friendly (which is so bad that the UK experiences "libel tourism": people visiting the UK to sue others). The state of UK libel laws is so bad that they are putting journalists at risk of being sued for investigative journalism (see trifigua or Simon Singh).
Please sign both these petitions, they are important and without acting on them we put health and freedoms at risk.