Heres a couple of tools I have found

Change history

Field survey papers

OSM contribution stats

OSM contribution heatmap

[mapillary’s OSM google street view analog] (http://www.mapillary.com)

[HOT OSM] (http://tasks.hotosm.org/)

[3D OSM] (http://demo.f4map.com)

[fixme’s on map] (http://overpass-turbo.eu/s/koS)

[open POI Map] (http://overpass-turbo.eu/s/koS)

[improve OSM] (http://improveosm.org)

[keep right] (http://keepright.ipax.at/report_map.php?zoom=14&lat=56.06445&lon=-3.21931)