I want a dataset small enough to be loaded in a text editor (with formatting turned on), but representative of the whole data. I want it for prototype scripts, but I dont want it to be missing stuff present in full datasets.
The smallest dataset I downloaded is 15MB. Is there smaller than 1MB?
Go to http://www.openstreetmap.org. Move to an area with medium-sized towns and zoom so that you can see the whole of a single smallish town. Click on the ‘Export’ tab. Click on ‘Manually select a different area’. Drag out a small rectangle, for example west=-0.6309, south=51.7446, east=-0.539, north=51.7791 (Berkhamsted, U.K.). Click on the ‘OpenStreetMap XML Data’ radio button then press the ‘Export’ button. You will receive a reasonably representative data set 1.6Mb in size. This example contains most road types except motorways, and is a good subset of typical OSM data. No data set apart from planet.osm contains every tag, of course.