So after having done that bike trip twice before without any mapping gear, I took a GPS receiver and my eeePC with me this time! The data includes some bike ways that have not been mapped before (opposite from Bremen steel factory; and from Huntebrück to Oldenburg). It also contains the main street of Lemwerder - that small city seems to have absolutely no mapping data so far. Hope to turn the traces into maps tomorrow.

Btw. though the eeepc caused some hassle at first (I didn't dare to fully close the lid, as the heat from the CPU might damage the display; so there was some blocker needed to keep the lid open a bit), it went quite well in the end. Data logging was fine with gpxlogger, at least after I noticed that its default interval of five seconds might be too coarse, and set the interval to one second; and by turning off Wifi and screen the eee managed to stay alive for four hours on battery.