As it was my birthday yesterday, I chose to highlight a birthday related application today. GBirthday is a panel applet that shows you which of your Evolution contacts have a birthday in next next few days.
There's no excuse for forgetting a birthday with GBirthday
This applet is customizable; you can show birthdays up-to the past 30 days and 90 days in the future. It even changes colour and flashes to alert you, so there's no chance of not seeing.
If you only have a few contacts you might not find this particularly useful, but people who have hundreds will benefit from having this reminder.