£0 - It may sound draconian but I think not giving them money is the best life lesson: if you want ££, you have to work for it.
Also, I think DCs should help around the house but I don't tie that to pocket money b/c the 'reward' for chores is doing them: clean clothes, tidy house, etc.
As per some others, I pay for what they need: food, transport, uniform, basic clothes, phone contract, music/dance lessons.
DD19 works at the local and earns well. She started at the pub shortly after turning 16 and doesn't often ask for ££.
When she's at university and thus not working, I give her £50/week for food but she pays for everything else: clothes, subs, socialising, phone. Her GPs give her some spending money each term.
DD16 has done some very lucrative cat-sitting and I will encourage her to sign on at the local now that she's 16.