I use quite a few of these Silverline TCT cutters. Cheap with a reasonable cut:

http://cgi.ebay.co.uk/1-4-SHANK-STRA...item2307ee4a3a

I've also recently bought, but not yet used, a spiral cutter a bit like this one. They shear the wood rather than rip across the fibre.
http://www.trend-uk.com/en/UK/trend/...ledge&id=15884