Karen Klein, one of my favorite columnists and bloggers, has an article in BusinessWeek with a year-end tax planning checklist for small businesses. 

In addition to the tax issues Karen Klein raises, I would add that this is a good time for small businesses to do the following:

(1) Corporations and LLCs should review their minutes book and make sure that minutes are up to date
(2) Companies with a Buy/Sell Agreement should review that to make sure it is still appropriate AND to do any annual valuations that the agreement requires
(3) Any contracts between a company or owner/shareholder/member should be reviewed to make sure they are still in full force and effect and still reflect the actual arrangement.  These include leases, employment contracts and loan agreements.

This may not sound like fun during the holiday season, but it will help you to sleep really well after your New Years' Eve festivities knowing that you have made an effort for your business to start the new year off with the legal and tax matters under control.