This scratches an itch for me. You had me at "accounting for Google Apps".<p>However, I tried to sign up with my Google Apps domain. After authenticating with Google, and redirecting, I received this error:<p><a href="https://app.rhinoaccounting.com/gaccount/callback/" rel="nofollow">https://app.rhinoaccounting.com/gaccount/callback/</a>?<p>Internal Server Error
A server error prevented this page from being displayed. The administrator has been notified and will investigate the problem as soon as possible.<p>There were a ton of query string parameters that may or may not be helpful in diagnosing the problem.