Depends on how small the business is we're talking about. QuickBooks or Peachtree are certainly meant for very small businesses. If you are "small" but rapidly growing you should be looking at the middle-tier with software like Blue Link
I agree with David that QuickBooks and Peachtree/Sage 50 are good for small businesses. We have a product called CenterPoint Accounting that offers excellent financial management tools and custom reporting, which many growing businesses find useful. It provides a wide variety of useful tools for growing businesses. Click here to learn more about CenterPoint Accounting Software from Red Wing Software
There are quite a few really good web-based solutions that you might want to consider as well. FreshBooks is pretty popular among small businesses, and they have a free 30-day trial on their site at Freshbooks.com, so you can see whether you like it before trying it.