I love Advent calendars. When I was a kid, my mom made a big felt tree on a burlap background as a wall-hanging, and made 24 little felt ornaments, each attached to a tiny safety pin so they could be "hung" (pinned, really) on the tree. The last ornament to go up was a Santa Claus face, that heralded that it was Christmas eve. Later, my brother got in to helping out, and we alternated days. His budding mathematical mind figured out that if he let me go first (on Dec. 1), he got to put up Santa, so I wound up insisting on an "every other year" situation so I got to hang the Santa once in a while.

(Now, my mother still puts it up, but has the cats "pick" the ornaments each day. [from what I've seen, they don't so much pick as stand there, waiting for their food, and finally they figure out that "hey, I need to do something to these things she's holding up, so I can get fed]).

Here are some links to online Advent calendars:

The Geffrye Museum, a museum that seems to feature "artifacts" from everyday life. Dec. 1's item is both charming and a little chilling, when you think about the background and history.

A British calendar discussing Christmas customs round the world

Leslie Harpold's Advent Calendar

A more religious calendar, with Bible verses. Begins at the ACTUAL beginning of Advent (Nov. 28). From St. Margaret Mary Parish.

Another British calendar. Click on the "fairy" icon (Americans would think it's an angel; it's more traditional for us to put an angel on the tree) to decorate the tree in a pop-up window.

Tate the Cat (an ongoing story with installments each day).