In the US they do a bran breakfast cereal called Fiber One which is yummy. It's very high fibre, low fat, and no sugar (unlike All Bran, Crunchy Bran). Has sucralose (which I know some people will avoid).
I wish they would release it here - sure it must be a HexB. Let's lobby them!
I've only just found these in the supermarket, they are bloody good aren't they! A bit on the small side but they're probably the first thing I've bought relatively low syns which feels that craving for the flavour of chocolate. The salted caramel ones are amazing.