FreshBooks, a leading online invoicing tool, just unveiled the official FreshBooks Add-on Store. It includes a free add-on for Highrise.
Combining Highrise from 37signals with FreshBooks makes it easy to go from managing leads, to invoicing them as clients. The Highrise sync tool lets you do this with a few clicks, no need to re-create your contacts in FreshBooks...As your contacts go from leads to clients, you’ll eventually need to bring them into FreshBooks for invoicing. All you need to do is add a tag to your contacts in Highrise, then login to the sync tool and pull your tagged contacts (or all of them if you want) into FreshBooks.
FreshBooks has over 60 Add-on partners and will be adding more to the Add-on Store in the future.