"I became self-employed in 2007 and was already using iCal to keep track of time I spent working for clients as well as keeping track of the duties I did for each one, each day. I would exporting my iCal notes into PDF form, create invoice by hand and then email both to my clients.

Discovering Office Time was a Godsend.

It imports all of my stuff, I hit "create invoice", put it in PDF form, and I'm done!"