Last night and earlier this morning I was mapping out coordinates to an area that I'm planning on placing a cache. I placed down a brick to mark the exact place I want the cache to go, and went back every half hour. I got a set of about 24 readings between 8pm and 8am to judge if theres much sway due to satelite position, and I'm feeling great that all my readings are comming up with very little "sway".
Comfortable with my readings I head back into the house to look up the coords on googlemaps. Holy jeez- the coordinates are putting me about 7 miles away in the next town east! I think "What the heck did I do wrong? " so I check the paper I wrote everything down on and compare it to what I entered... Exactly the same. So I try a couple different internet maps, each one puts me in the other town.
I started to get frustrated, and went back out to my brick and read the coordinates one last time. The GPS gives me W 092 59.455 ... compare that to what I wrote down every single time - I had W 092 49.453 to W 092 49.459
Put the updated coords from the last reading in, and TADA- I'm in the right town, and practically on top of the actual area according to the satelite.
Gah, I can be so dumb sometimes. Just glad I verified with the maps before actually saving the coords!