I may be naive about this, but it seems like an Open Source small business accounting package could become very popular. The major advantages would be 1) the visibility of the underlying data, making it possible to export any/all of the data to any other application; 2) the ability to integrate with any other application, such as creating a web front-end that would feed data into the business management systems. This is as opposed to products like QuickBooks, which keeps _my_ business data locked up in _their_ proprietary system, making it hard for me to get my data back out for use with other applications. OTOH, QuickBooks does make critical business operations -- like payroll, and tax reporting -- fairly easy to do. And I've yet to encounter any QuickBooks bugs or crashes.
There are dozens of "accounting" projects at SourceForge, but only SQL-Ledger seems to have gotten beyond the planning/alpha stage, and it is based on Perl <cough>.
