software for handling waypoints, tracks, etc

• Garmin Basecamp (free)
• Garmin Express (free)
• Garmin Mapsource

• QLandkarte GT

software for creating Garmin .IMG maps (vector)

• premade maps!
  • garmin.openstreetmap.nl web service
• mapwel ($90)
• GroundTruth (free/OSS) (wrapper for cgpsmapper)
• OSM Composer (free/OSS) (wrapper for cgpsmapper, mkgmap, srtm2osm, etc)0
• mkgmap
• cGPSmapper
• GMapTool
• Osm2garminGUI
• more

software for creating Garmin .JNX maps (raster)

• MAPC2MAPC ($16)
• OkMap Desktop (free)
• whiter.brinkster.net (format description)

software for creating Garmin .KMZ maps (raster)

• MOAGU (Mother Of All Garmin Utilities)
• MAPC2MAPC ($16)