From OpenStreetMap Wiki
This table shows support for tags in various tools:
- Mapnik (OSM.xml, ogm2psql)
- Osmarender 
- JOSM (core/styles/standard/elemstyles.xml) 
- Kosmos 
- Potlatch rails port (git://git.openstreetmap.org/rails.git : rails/config/potlatch/presets.txt and autocomplete.txt)
- Wiki (Map Features)
- OSMdoc (tags in actual use. only tags/values that are also recognised in one of the other sources are shown, with a few exceptions. File prepared by Lars Francke)
All input data current as of May 17, 2010. Except OSMdoc data: December 2009.
Generated by automatically parsing source code.
Total recognised keys: 204
Total recognised key/value pairs: 1474