Thanks to Michael Lucas-smith, we have a new, beautiful home page. Owe you a pint, Michael!
Check it out: http://pongo.sourceforge.net
TONS of new features!
Pongo now keeps statistics for all your contacts, watching when they go online and offline to help you predict when your friends are going to be around next. Right-click on a contact and select "View Activity Profile..." to see the graphs.
Initially you won't see anything because Pongo has no data. Leave it running for a few days and see how accurate it is.