Waldi is a tool to read GPX tracks and semi-automatically post found logs to Geocaching.com
It's a bit finicky and mostly suited to my personal needs.
You'll need to set the following environment variables:
GC_CONSUMER_KEYGC_USERNAMEGC_PASSWORDGC_API_URI
Consumer key, username and password are optional and if provided will be used to automatically post logs to Geocaching.com.
The API URI is used to lookup geocaches from my query server.