I've arrived at this site looking for UK Waterways features in OSM. Currently need to read up on how to contribute to OSM, but think it would be good to see if UK boaters can join in the effort to add useful canal features. I can be contacted via skype and twitter with the username gklyne, or email to gk-openstreetmap (at) ninebynine.org.
My (possibly relevant) background is as a web software developer and a UK narrowboater (nb Urquhart Castle).
Starting my investigations at WikiProject_United_Kingdom_Waterways.