The Messier Marathon
Messier Marathon web site explains history, controversy, and search sequence for attempting to find as many Messier objects as possible in one night.
Includes a gallery of Messier objects, Herschel 400, and the Deep Sky Browser, an easy to use front-end for the Deep Sky Database which includes information for deep sky objects and stars.
Ultimate Messier Object Log, The
Freeware database that contains relevant information for all 110 Messier Objects and various layouts to assist amateur astronomers in documenting their search for deep sky objects.