The almanak is broadcasted along with the GPS signal -- so it is important that you allow your GPS to download the new almanak and other corrective data once in a while. See the details here.
For us geocachers, a precise fix is very important! We don't want to dig through a whole forest to find the cache. Which is why we will be participating in the National GPS Recalibration Day.
We are going to N51 54.216 E4 09.866, because on 12:15 precisely, there will be many sattelites directly overhead. We'll try to get a fix, and download the almanak in parallel, for a speedy recalibration.
See you GPS receiver owners there!