I know we said we would not start listing Web sites, but here are a few links to sites which offer fully operational tools running online that we feel are especially useful or interesting, from a browser on any platform.
Clear Sky Clock will show at a glance when we might expect clear and dark skies for one particular observing site.
The Simbad astronomical database provides basic data, cross-identifications and bibliography for astronomical objects outside the solar system.
Cluster simulator NEWS 2007 - WE CANNOT VERIFY THIS PROGRAM - DELETION SCHEDULED
Sky Image Processor an astronomical image processing program which runs over the Web. Hosted at Virginia Tech.