I've experimented quite a bit with Mobile Sat Navs, as I was keen for it on the bike. I was/am still hoping to do blasts around Euroland. One ability of the expensive Garmin bike units is to plan ahead, design a route on a PC, researching where is best to go, sights roads ect, and plot it in. As it won't be a direct or fast route, it has to be manually plotted.
But they are super expensive, around £400

I tried Navigon, even made a how2 on the GS forum:
http://www.ukgser.com/forums/showthread.php?t=260843&highlight=customBut all of them suffer with GPS positioning, as the surface to get a signal is small. On camping road trips with mates off in Cornwall or Wales, it really struggles at times.
Often in Scotland and Applecross area, I had zero signal, so data based maps are useless.
I've used TomTom on my iPhone while in Greece/Portugal on holidays, they work to a degree, found it very useful in Portugal for finding a supermarket. But it struggled in Greece, though the maps were a bit crap. I'll continue to use it for trips abroad, but in UK i'll either use a dedicated unit or map print out.
Last time I went somewhere I'd not gone to before, I just wrote down key junctions for motorways & roads, just before I left I checked Google Streetview to see what buildings to look out for.
Worked a treat going into central Bristol to pick up MrsT
