Seriously? LibreOffice Calc.

If linux had even a *semi* decent accounting program I believe a LOT more companies and individuals would be willing to use linux on the desktop. Unfortunately, they all suck. Badly.

http://moneydance.com/

Is by far the best, though it is not free and better for personal accounting, not for a business. It is getting better at the business side.

GnuCash is an accounting program but it is so complicated to use it is not worth the time or hassle. Sorry Mike!

I used one some time ago that was actually really good, but the company made it gargantuanly expensive and it competes with Peach Tree accounting software.

Your last bet is:

http://www.linuxledgers.com

http://www.ledgersmb.org/

http://sql-ledger.com/

Good luck installing them!