I think it's pretty cool to get things signed in person, face to face with the artist, but it's not that I drag out all my CD-booklets to concerts hoping te get them signed all the time. Also buying something signed on ebay for instance has less value, though I did buy a Death "Human" LP signed by Chuck last year, that's pretty awesome I think.
Also I have 2 copies of the Blackfield LP signed by Steven Wilson, I bought them from Michael Piper, the guy who does most Porcupine Tree and related vinyls and he told me he would meet SW the day after I ordered my LP's, so I asked if he could get SW to sign them, which to my pleasant surprise he did!