MicroCalendar

MicroCalendar is a tiny calendar that sits in the Windows system tray, always just a click away. Find out what date the first tuesday of last month was, WITHOUT messing up your system's date, OR having to fire up a resource-intensive application like Microsoft Outlook.

Also allows simple copy-to-clipboard functionality, and can display week numbers. This is a streamlined, super-clean, single-purpose application, without the clutter of unneeded features -- just what you're looking for! : )