Here's a post for files I mention in the OpenOffice.org 3 Guidebook.
Calendar created using a spreadsheet. I've included a 2011 calendar, a very simple one created in Calc. There's one with the formulas in it, and one with just the numbers.
Solveig Haugland: The OpenOffice.org 2 Guidebook: Amazon
Solveig Haugland: OpenOffice.Org 1.0 Resource Kit