I replied on a thread that was three years old the other day...and then thought, what the heck am I doing! This doesn't matter anymore. I felt pretty silly, actually.
Taught me to look at the posting date when I read the article though! LOL.
That said, if I am the last poster on a thread with no replies too many times in a row I start to feel like a thread killer...or that maybe I have cooties. ; D.