Great Britain and Ireland Location Information. Lots of reference information and a handy location coordinate converter including Lat/Long, NAC, US Zip and UTM or even GB telephone area codes post codes and motorway junctions, and a gazetteer for place names.
"The Society exists for the discussion and education of roads in Britain and Ireland. Anyone with an interest in British or Irish roads is welcome to join and participate."
If you realy need to know somthing about roads or a specific road; these are your experts!
POI Editor lets you view, edit and convert Points of Interest files from GPS devices such as TomTom, Navman, Garmin and many others.
A web based route planner that works on most platforms and targest most GPS devices.
The only way I know of planning a route on a tables then transfering it to yous GPS device.
Also has route and track sharing facilities and an integrated phone app.