Slowly whittling away at an online accounting suite for small businesses. Stubbed out the underpinnings, and just did the first major design iteration. Should show it to the first potential users in a month or two.
There's also a number of web based accounting software, like the online version of Quickbooks, NetSuite, and Intacct.
Glad to hear there's a market for it.
I'd love to hear more about this... make sure you keep hacker news posted!