I've learnt that one can add annotation on maps on OpenStreetMap by adding
- box=yes&bbox=
lon1,lat1,lon2,lat2to draw a rectangle and - mlon=
lon&mlat=latto add a marker
e.g.
http://openstreetmap.org/?box=yes&bbox=-1%2C51%2C1%2C52&mlon=0&mlat=52
What other drawing parameters (most importantly, text, if possible) can one add to OpenStreetMap URLs? It must be a simple URL I can email to someone, so no using APIs or running my own webserver.