I've hacked up a viewer program that runs on Windows Mobile using CartoType, my map rendering library (www.cartotype.com). The UK OSM data compresses down to about 27MB. The style sheet gives a display that looks very similar to Mapnik's rendering; the viewer renders on the fly and the map can be zoomed out to show the whole of the UK, or right in to street level. By this evening I should have the program, data file, and style sheet up on the CartoType web site for free download; and also the data conversion tool, so that anyone who wants can make new CartoType map data files (CTM1 files) from OSM data.

I'll also make the Windows XP version available. It uses the same data file.