Oliver has produced OpenOrienteeringMap, an orienteering map based on OpenStreetMap data, in two formats:

The Street-O map contains the level of detail equivalent to the Street-O maps used for informal orienteering races around the streets of London and other urban areas in the UK and around the world. The Pseud-O map is a less serious map (as the level of detail in OSM is not sufficient for “proper” orienteering maps) but attempts to emulate the look and feel of standard orienteering maps.

Both maps make (loose) use of the ISOM and ISSOM orienteering mapping specifications, particularly the colours and the styling. Measurements are less likely to be within spec, due to artistic considerations and limits of standard screen resolutions.

Oliver explains things here and here. Via geoparadigm.