Map made by deLorme MapExpert
This is where the US satellite Global Positioning System (GPS) thought my house was for a few hours one afternoon. Lively old place, isn't it?
The grid-like arrangement of the dots is caused by the resolution of the data format used by NMEA0183. It only gives the location to a few places of precision, so even if the GPS data was somewhere in between, the transmitted data is going to be rounded off to the next highest or next lowest latitude or longitude and will be plotted that way.
BTW, that data was collected by a Micrologic Sportsman (handheld) GPS with no differential (DGPS). I now have a fancy Northstar 951xd which has built-in differential, and claims to be able to locate me to within a few tens of feet. Based on where it puts the position of my boat on the built-in chart-plotter, it seems to be living up to that claim.
I haven't figured out a way to transfer an image from the LCD screen of the Northstar to the computer; besides, a picture of a map with a dot that stays in the same position isn't very funny anyway.
For automobile GPS work I have a couple of things that I use regularly.
deLorme Street Atlas 6.0/Tripmate combo: I like it a lot. I use it any time I am taking a long trip where I will be taking my computer anyway. Also if I am going to an unfamiar city. I like the address to address routing, and route planning features. If you plan to travel with a computer, this is a pretty good solution. The new deLorme mini-GPS only "speaks" to deLorme products, which I think is a move back to "the bad old days" when manufacturers tried to lock customers in to their own line of products by deliberately making them incompatible with other products.
Garmin StreetPilot: This one stays in the car all the time. I turn it on even in familiar territory, just because I like gadgets. The MetroGuide cartriges are expensive, and limited in coverage, but they seem to be accurate enough. It doesn't do address to address routing, but you can do it manually fairly quickly. Supposedly a color version is due out in Feb. 1999.