Just a few solutions I found with a quick Google search:
http://www.sportys.com/acb/showdetl.cfm?DID=22&Product_ID=1167
http://dsafe.stores.yahoo.net/vlmo25.html
http://www.strongholdsafe.com/zcart/index.php?main_page=product_info&cPath=1&products_id=207&zenid=6e64d13e42d868eec2cd6d03457766c4
If you intend to leave the gun in a desk drawer all the time, be sure you perform due diligence with your state laws regarding handgun storage.
Additionally, you will probably want to
- Select a locking desk drawer
- Use a safe that can be bolted down
- Has metal plate(s) to protect against prying
- Secure the drawer or safe with a cable inside the drawer space.
If your desk drawer is locked and a thief opens it, if he tries to take the unit the cable has to be cut, then the safe pried out and opened. With all that, no one can claim you didn't go the extra mile to prevent its theft.
Depending on your business, the best place for your weapon is on your person. In legal offices, lawyers often meet clients in their offices. Other businesses use a conference or meeting room for privacy. If you're not in your office when things go bad, having the gun may do you little good.
Lastly, your "office gun" should be kept squeaky clean. Always. Never store it dirty after shooting at the range. This allows you to detect if the gun has been fired and returned to your desk.