wClock (88Kb donationware) displays the time and date in the menu bar. The format, font, and color of the menu-bar display are fully configurable. wClock also provides convenient one-click access to a monthly calendar.
I’ve been using PTHClock as my menu bar clock and was very happy with it. However every time I used the drop-down calendar it would quit. I’m giving this one a try to see if it behaves better.