There's a lot of fly fishing books out there and a lot of fly fishermen like to get their books autographed.
Most authors will incribe your book with something like:

To Joe Fisherman,
hope that nymph works out for you,
Tight Lines,
Charlie Author


... or something like that
Unless the book belonged to another famous person, I doubt this does much to increase the value.
A plain signature would be worth more for resale.


Do you collect author's autographs? Do you do it for your own satisfaction, or do you think it increases the books value?
What one would you like to have?