The somewhat awkwardly named Worked All Prefix award is given to amateurs that have worked 300 or more "prefixes". A prefix is the combination of letters and numbers that identify a country (or entity) plus a region number within that country. For example, my call sign is NE1RD. The NE1 is the prefix; the RD is the suffix. Searching and sorting through my pile of QSL cards was an interesting exercise when completing my application for this award. This was done around 2006.
Fast-forward now to 2013. The ARRL Logbook of the World (LoTW) now supports the WPX Awards program. It is now possible to use QSLs from the LoTW system for CQ Magazine WPX award credit. Just click and win! I have now collected the following WPX awards:
I am now working towards the WPX Award of Excellence. That will take a lot more work--but it should be fun! (I just need AF, AS, and OC mixed to qualify.)