As the New Year approaches, updated calendars are a great way to help students and parents get organized. Teachers should consider giving this link to parents, so they can download a blank calendar for placement on the refrigerator or bulletin board.
Every day when the child comes home, he or she can write in their homework assignments, and parents can easily check it.

Astronomical Calendars

DateDex
Great link to days around the world and a lot of special ones -- always kept current.

Free Printable Calendars (monthly)
A huge variety of calendars

Holiday & Special Themes
Calendars for many notable dates in United States

Preschool Printables: Calendars

Time and Calendar Activities
Find printable calendars and themes for younger students.

Time and date.com
All types of calendars -- great for world history and culture

Web Calendars
All types -- some quite esoteric, some useful, all of them of note