I noticed this on the gc.com forums a couple of weeks ago and I thought it was kind of cool. Perhaps old news by now, but there is a website that you can use to verify puzzle cache solutions. Cache owners place a special link on their cache page that will allow puzzle solvers to enter their solution to the puzzle to check whether they are correct coordinates. I like it because people who need to travel a long distance can feel confident that they have the right solution before heading out, and can get instant verification as opposed to having to wait for an email sent to the owner.

Security seems not to be an issue since no data is stored on the server. Instead, the solution is encrypted in the URL – pretty slick. Plus it counts the number of guesses so it will prevent you from trying over and over until you get it right. Someone pointed out that it’s much easier just to solve the puzzle than try to hack the site for the solution.

Here is the site:
http://www.geochecker.com/

Here is another one that appears to do the same thing:
http://evince.locusprime.net/cgi-bin/index.cgi

If you want to see it in action, I use the first one on one of my caches: GCPCE1 (<-- note auto-hyperlink - thanks Jeremy!) Finally here’s the original thread on the gc.com forums:
http://forums.groundspeak.com/GC/index.php?showtopic=136661