Pocket Queries are a premium member feature of geocaching.com. They allow you to search for caches with the features you want and have the results delivered to your email. Some of the parameters you can search against are:
- Cache type
- Cache size
- Whether you have found or not
- Whether you own it or not
- Recent activity
- Date placed
- Terrain and difficulty ratings
- Location by country or proximity to a specific spot (like your house).
You can get up to 500 caches in your email, and the file includes all the cache information (hints, owner, logs). The file is delivered in GPX format.