Matt Gemmell, on not waiting until someone is dead to tell them what you think of their life's works:
[…] Imagine if it were you instead. Wouldn’t you want to know?
It need only take a moment; 140 characters are more than enough. Believe me, each one counts. If they’ve made something that reached you, and – even just for a moment – left you better than you were before, don’t just move on. These are people, remember; like you. Don’t wait.
Tell them. Tell them now.
Tell them while they can still hear.
Matt takes it a step further beyond just speaking to your friends and family while they are still here. He extends the notion to those you take enjoyment from. Writers, artists, etc. If you found enjoyment in someone's work, tell them.
The closest example of this that has happened to me in recent memory is after I read a book last year titled A Drive into the Gap by Kevin Guilfoile. I wrote a review, mainly for myself, in Day One, and on a whim decided to use their new Publish service and I linked it on Twitter.
Not long after, Kevin reached out to me on Twitter. We chatted about his dad a bit. I thanked him for writing a story that ended up having profound effect on me.
That's what Matt is getting at. Say thank you to those who have great impact upon you. Say it while they are around to hear it or read it. Bless them as they have blessed you.