Terraserver is pretty good. If really hi-res images are available for your area, you will have to buy a subscription to download them. They charge a lot to download really large images. I found that there is 6" resolution available for the area where I live. Free viewing only allows you to see 8-Meter resolution at the most. Even when you buy a subscription, the images you will see on your screen are about 6" square....probably about 400 X 400 pixels or so no matter what the resolution.
So to get a rather large image, instead of shelling out 80 bucks for a 2000 X 2000 pixel image, I bought a week's subscription for 10 bucks, screen captured about a hundred of the small hi-res images from all around my area, and then did some photo shopping for a week or so to create a large super-hi-res collage. If I were to print it out, it would be about 5 feet square.
That said, there are two new products that are competing toe-to-toe with Terraserver.com:
1. Google Earth
2. MSN Virtual Earth.
Especially in the large metro areas, you can get hi-res images for FREE. Google Earth has other great features, like the ability to tilt the image so it looks like you are flying over the area. And in large metro areas like NY or L.A., there are crude 3-D images of the larger buildings (as in "skyscrapers").
Google Earth is cool, but it and MSN Virtual Earth do not always have the same hi-res images that terraserver.com has.
Google Earth has horribly bad imagery for the area I live in . MSN Virtual Earth is somewhat better, but it only has the 8-meter resolution black and white images that you can get for free on terraserver.com. So in my particular case, Terraserver.com yielded the best imagery, though I had to shell out a little money and put in some time & effort to create my large hi-res neighborhood image.
Despite the Big Brother aspect of it all (*SIGH*), it is very helpful to have such tools available for us. One obvious tool is if you are looking at real estate (buying a house, perhaps you might want to know what the surrounding neighborhood is like).
A useful thing for us here at treasurenet.com might be (if it is hi-res imagery) that you can see old abandoned roads/trails, etc. and perhaps see where buildings used to be. As the CIA discovered early on, there is much you can learn from above that you might never see on the ground.
And of course, as time goes on, and the satellite imagery gets better and better, more hi-res imagery will be available to us.
One other thing. Perhaps I have not fully explored the features of Google Earth or MSN Virtual Earth, but terraserver.com will tell you the exact date when your image was taken. The images I used for my neighborhood collage were taken in May of 2000. I have not seen in the other two services any place that would list the date of the imagery.
Hope this rambling paragraph helps someone.
? HECK! I was stunned!? 
