Worldclock
This is a simple application written in C and using fltk-1.1 for displaying the time in various timezones.
It is fully customizable from the GUI and uses the system's timezone files in /usr/share/zoneinfo for calculating time.
The latest version can always be installed with:
opkg install http://www.crash-override.net/~blindcoder/ipk/fltkclock.ipk http://www.crash-override.net/~blindcoder/ipk/fltkclock-doc.ipk