I've been using the expensive Ansmann chargers, but after both failed and recieved no response to my emails from Ansmann I bought the following at Maplins.
I've been running this charger on a daily basis for several months now and must say I'm extremely pleased with it, charges from 1-4 in less than 30minutes. Some of my older batteries would not charge using this charger, but all my newer ones do without problem.
http://www.maplin.co.uk/Module.aspx?ModuleNo=45798