Is this the platform for feature requests/enhancements?
Because there is a feature that can be valuable for geocachers caching together (aka friends ).
If you would be able to say "today I'm caching with my geocaching friend x, so show me all the caches near y that neither of us has found yet", you can easily go looking for caches together.
At work I have several colleagues with whom I cache during lunchtime. But it's not always the same person, so now we select a cache, manually check whether the other one has already found that cache. If so, we try to find another one. When the number of caches found increases in a certain area, this gets rather time consuming. A simple query that takes friends into account can solve our problems and is a nice feature to have (at least that's what I think).