Constellations is an excellent reference for considerable information on the constellations by Richard Dibon-Smith
Heavens-Above is a great site for a variety of astronomical information. Want to know when the next time the International Space Station will be passing over your house? Want to find out what comets will be visible, where and when? Want sunrise or sunset or moonrise or moonset times? How about constellations? Satellites? And more, it is one of the best resources available.
In-the-sky.org is a site with observing data galore tailored to your location.
JPL Horizons Locate anything in the sky
Night Sky Info – Monthly information about the night sky and articles on selected astronomical topics.
Sky Maps is a one of the best sites for printing monthly star charts or sky maps if you prefer. The maps even give you the best objects for naked eyes, binos and telescopes. The site also is a great resource for other tools such as books, etc.
Stars is a comprehensive site of detailed information on stars and constellations, highly recommended.
Stellarium Planetarium Software One of the best and easiest open source planetarium software available and it’s free!
The Constellations The 88 Constellations, names charts and tables from the International Astronomical Union.
Tonight’s Sky is a real nice place for determining what is visible in your night sky tonight. You can choose your preferences