I ususally slip it into the book, and hope that I can either see the author in person (thus freeing up the bookplate for another volume I may aquire in the future) or I find the freakin book that is hiding from me after the author leaves town.

Its difficult to take a lot of books on an airplane, your luggage always gets inspected because its dense and resembles some devices or something... and its a hassle to FedEx them to the hotel... haul them around .. I ususally can accost an author and request a signed bookplate or three without having to run back to the room, find the books if I brought the specific author, and then hunt them down again. The last few large Cons I went to, I was a PA, so I had even less chance to do that, (shhh, I be huntin Awthors!)

I just have too many books in my place, and some have gone feral on me.. skulking around, hiding, teasing the cat...