Star maps with constellations may be found on stargazing.net, astroviewer.com and stardate.org. Neave.com also offers an interactive online planetarium that includes constellations and can be customized to display images based on the user's location.
Stargazing.net has a variety of star maps freely available, including maps with stars and constellations labelled and an inverse-color sky map with black stars and constellations and a white sky. Astro Viewer also hosts an interactive online night sky map, as well as offering a downloadable version of the program. Star Maps releases a monthly guide to the night sky called The Evening Sky Map, which includes maps of planets, stars, and constellations.