What about a small scrapbook of pictures of him/family?
What about a small book of his co-workers signing a small book or putting a picture of themselves/writing a little bit about them,etc...?
I would say something Monogrammed from Things Remembered. They have neat gift ideas.
When my Mom retired from University of Kentucky, where she worked. She is a big basketball and football fan. The co-workers got some cool pictures of the basketball team and football team, the mascot, the coaches signatures and had it framed in blue and with the UK logo. That was a cool idea and she loves it!
Does he have a sports team or a favorite college team or did he graduate from college? You might do something like this and contact the college about doing something like this. I guess you would have to talk to someone in the sports area or go to the bookstore for memorabilia.
My Mom got a digital camera several years ago from my Uncles. Does he like to take pictures? You could get him a new digital camera. If he likes taking pictures, maybe something special from Wolf Camera, a special addition to his camera.
It would help knowing what hobbies he has or favorite activities/what his job was, what he plans to do in his retirement,etc...
Hope this helps.