Riverbend Community Math Center - Dean Serenevy
We are a US not-for-profit (http://riverbendmath.org/) using SQL-Ledger and LedgerSMB since 2006 (I'm not sure exactly when we made the switch). We are a small organization: ~15 part-time employees; ~$150,000 annual revenues; 2 users of the ledger. We are still using 1.2.x because my trial transition to 1.3.x did not work out as smoothly as I had hoped. Thus, I have put the transition on hold until I can give it a few days attention. As an organization we believe in and use open source software almost entirely.