The idea is to produce a sheet of paper that the area can be mapped on, where any existing features (e.g. large roads) are pre-plotted, and a map can be sketched in reasonably accurate detail using just the grid and a handheld GPS.
Main feature is lat/long graph paper that makes it easy to read a position from GPS, and plot that on the map without any measurement tools.
Will need to display segments obviously, with some indication of what level of detail already exists for that street (e.g. does it have a name, does it have a class)
This might need to work on greyscale printers, e.g. don't put too much information in similar-brightness colours.
Might try to display street names, but it might be easier to give each street a label (AA-ZZ) and list what names they represent on the side (doesn't require rotated text, etc.)
Will need the latest data for this sort of thing, to prevent duplicate work (i.e. no planet.osm from months ago) - since it will typically be small areas, see what download scripts (e.g. wget) are usable
Code should be as simple as possible, so that it's easy to script a reasonable number of pages, e.g. for segments along a long-distance path, or for peoples' allocated areas on an OSM Workshop
Someone's going on a journey, and wants to sketch side-roads, features, villages, postboxes etc. as they go past them, keeping track of their position on an A-road that's already been surveyed
When you're mapping an area, and want to do georeferenced sketches so that your road names are all in the right position.
When an area like London has already got loads of segments, and you want to mark the road-names just by writing them on the map, rather than going through the long-winded methods like timestamped cameras or waypoints.