DateInTray is a small freeware utility that displays the date in the
Windows tray.
The day of the month is displayed in the DateInTray icon, and the entire
date can be seen in a tooltip popup by holding the mouse cursor over the
icon.
A useful popup calendar can be brought up by clicking on the DateInTray
icon. This easily accessable calendar popup is very useful when you need
to quickly reference a calendar. The calendar popup automatically shows
the current date, and include arrow buttons to easily view next and
previous months.
DateInTray can be easily added to the Startup folder in the programs
menu so that it automatically starts every time you log in.
http://www.crispybytes.com/dateintray/