A few that I swear by: github http://github.com http://github.com for source control and wikis sendgrid http://sendgrid.com http://sendgrid.com or Amazon SES

A few that I swear by: github http://github.com http://github.com for source control and wikis sendgrid http://sendgrid.com http://sendgrid.com or Amazon SES for email mogotest http://mogotest.com http://mogotest.com for browser testing recurly http://recurly.com http://recurly.com for managing recurring payments tender http://tenderapp.com http://tenderapp.com for support / help desk linode http://linode.com http://linode.com for hosting or Amazon EC2 mocksup http://mocksup.com http://mocksup.com for quick and easy mockups clicky http://getclicky.com http://getclicky.com for analytics zerigo http://www.zerigo.com http://www.zerigo.com for dns and monitoring AWS http://aws.amazon.com http://aws.amazon.com S3, EC2, and everything else :)