My first efforts with OSM has been to map footpaths in East Rock Park in New Haven, CT. For the past several months when I walk the park I make a trace with the Garmin GPSMAP 62. I have been accumulating the traces in a single GPX file.
I have used mkgmap to make an img file which I can download to my Garming GPS. Currently I am trying to learn how to use TYP and styles to make a better walking image on my Garmin.
I have also been adjusting local streets based on Bing imagery.