not really mastering related, but i remember some threads in the "So Much Gear..." forum....
i use iBiz and iCal. thats it. im small time, low overhead, so this works for my one man shop. but i can totally see a need for a more robust solution esp if u manage employees.
my wife uses quickbooks at our bakery.. i absolutely hate it! the newest version is a pox on my brain, i dread doing payroll (for other reasons besides shelling out tons of money to no good lazy employees
)
good luck :)