The oxfam brand of chocolate is great for those who like cadbury style chunky chocolate like I do - sooo yummy! You can buy it online now (they used to not post chocolate because of the melting factor).

Cadbury Range - including Picnic, and Fry's Turkish (owned by Cadbury Schweppes) EDIT: 5 March 2009 - Cadbury UK has announced that they hope to have gained Fairtrade accreditation for their Cadbury Dairy Milk range by the end of 2009!! To date they have not said anything about applying for Fairtrade accreditation for their subsidiaries too (including Cadbury Australia). So watch this space!!
Now that would be awesome!