In the UK, you can text GIVE to 70077 and £5 will be added to your phone bill and given to DEC for the Haiti relief appeal.
This number was previously used for Children in Need, then the network operators waived transaction fees for doing this, O2 – who set up the above – have said they are doing that again, I do not have documentation for other networks.
DEC and the Red Cross are good people to donate to for this. There are a number of scams running under the name “Donate to Haiti”. Sometimes humanity sucks.