Good suggestions!  The golf thing sounds like it won't work though, my work area is directly outside of his office.  No noisy toys.    The letter opener or leather folder sound like good ideas, the customized golf balls sounds like what I'll get for him for Christmas.

Here's some more suggestions for those in the U.S., makes great thank you gifts, birthday gifts, etc.
www.harryanddavid.com
www.ediblearrangements.com   <-- my new favorite!
www.winecountrygiftbaskets.com
www.cookiesbydesign.com