Geocaching Street View v2.0.2resigned1
This extension replaces the basic map on geocache pages with a split map that shows both the aerial photo and the Google Street View (if available) of the cache location.
You may need to supply your own Google API key. Instructions are available from the settings page, which is accessible from the small gear icon above the map.
If you have the Street View 1.x Greasemonkey script installed, you will need to uninstall it before using this extension.