This Geeklet tells you how long your Mac has been on for (e.g. Up 3 days, 22 hours and 28 minutes).
It is quite easy to rearrange the output format to what you want. The command is:
uptime | sed -e "s/:/ /2" | sed -e "s/,/ /2" | awk '{print "Up " $3 " days, " $5 " hours and " $6 " minutes"}'
As you can see, $3 will print the number of days, $5 the number of hours, and $6 the number of minutes. You can rearrange these, for example:
uptime | sed -e "s/:/ /2" | sed -e "s/,/ /2" | awk '{print "UPTIME: " $3 " days, " $5 ":" $6}'
will give UPTIME: 3 days, 22:28 instead.
