OK, the water question again. I hope I'm adding something here rather than repeating an idea that's already been discussed.
I've done a bit of geoconverting but as I'm mainly interested in the UK the big issue is water. Editing the coast takes ages. Now we know that sharing scenery is somewhat iffy copyrightwise (and data storage/bandwidth wise) but I was wondering if we can come up with a way of sharing coastline masks. Now that one of our own (i.e. nickhod ) controls the tools there is the option to create a masking system that can be input with the tile downloads. One quick thought is that instead of throwing away the original pre-edited tile there could be an option to input the edited and pre-edited in order to generate a mask as a by product which can be uploaded somewhere and used by others.
Even slicker is to combine geotiles with coastline vector data which OS Data provides for free. DIfferent systems for different regions here though. Perhaps we need working groups for different regions.