This page contains links to the various web sites and other resources that we found useful in creating SkySafari and SkyFi. It also lists a few other sites of general interest to amateur astronomers. A few sites are listed more than once under different categories: for example, we found the HubbleSite to be an excellent resource for both solar system images and deep space images.
There are, of course, two other internet tools of great use to astronomers: Google and Wikipedia. However, as these are only content indexers or compilations of other material, we thought it might be better to bring you directly to the sources that we've found the most useful.