As you start geocaching more and expanding your search radius beyond the confines of your own neighborhood, you'll begin to find that the pocket queries you download are getting bigger and containing more geocache listings. At this point, you're going to want to use a program that can maintain your GPX files (contained within your pocket queries) and help manage your growing lists of the geocaches you have found or plan to look for in the future. There are a number of free tools available that can help with this task, including ClayJar Watcher, EasyGPS, and GPSBabel. But for my money (free trial/$25 registration fee), one of the best, all-in-one, personal geocache database and GPS file format conversion tools is Geocaching Swiss Army Knife, or GSAK.
I use it on a near daily basis to not only manage my various lists of GPX files, but to also convert those files to Google Earth and Google Maps file formats so I can view the locations of previous finds or upcoming hunts. The tool also lets you sort and filter your data so you can view, and send to your GPSr, just the Geocache listings you want at the moment. It's like an Excel program specifically for GPX (geocache) files!
Here's the official description from the web site:
GSAK is the all in one Geocaching and waypoint management tool. Major features include: Multiple databases, sending/receiving waypoints to GPSr, Google maps, conversion to many mapping formats, PDA output (including CacheMate support), HTML output, extensive searching, macro support, backup and restore, distance/direction from other waypoints (including caches, locations, post codes) and much more.
In addition, the GSAK forum is very active and covers every GSAK-related topic you'd ever need, from FAQ's for beginning users of the tool, to detailed information on writing your own GSAK macros. The GSAK software developer himself regularly contributes posts and responds to questions in the forum.
There's so much more to say about GSAK, but it'll just have to wait for future posts. But believe me, this is one geocaching tool that's worth every cent.