The project at http://www.openstreetmap.org/ tries to create a copyright free routable vector map from gps traces and other sources for example viewable with Marble allready made portable at https://portableapps.com/node/23501. The basic stand alone tools to add data to the online database are
Merkaartor at http://wiki.openstreetmap.org/wiki/Merkaartor and
Josm at http://wiki.openstreetmap.org/wiki/JOSM .
JOSM is an java app and already quite portable except for storing plugins and other data on the local machine. A one click installer that links this app to the java installed on the usb-stick and takes care of setting a path to the portable device would be neat (solutions described here: http://josm.openstreetmap.de/wiki/USB_Stick here http://josm.openstreetmap.de/ticket/1628 and here http://wiki.openstreetmap.org/wiki/JOSM/HOWTO/Run_from_flash_disk_with_Java).
Something similar would also be great for the gps viewer Prune at http://activityworkshop.net/software/prune/ .