I use shampoo and conditioner for coloured hair, I think it's elvive, the one Cheryl Cole advertises? Right now I'm using that garnier green bottle stuff though cos I bought it ages ago and ran out of the other stuff so started using that until I get more. I just got my hair cut shorter than it's ever been, it's so much easier to wash now!
Edit: just checked, it's garnier fructis. There is a shop here that sells all the good brands of toiletries for just 1.49 each, compared to I don't even know how much in other shops, 3 or 4 euro at least probably. So that's great for me.