Fresh books is an online invoicing software as a service made for freelancers, small businesses, agencies, and professionals. The product includes a myriad of other related features, such as time tracking, expense tracking, recurring billing, online payment collection, the ability to mail invoices through the U.S. Post, and support tickets.

Ambiguous name, uptight style dumped in favour of breezy, open communication. Called the next big thing in Social media. I use it so should you!

They even have a OSX dashboard widget and iphone app