Pet peeve of the moment: People who go on vacation, turn on their stupid vacation autoresponder, and can't be bothered either to set it up not to spam the mailing lists they read, or to temporarily turn off delivery on the frelling lists until they get back. I just answered a question on sunhelp and got spammed with no less than EIGHT vacation notices in three languages.
It's bloody inconsiderate, not to mention rude. The odds are that fifty thousand people worldwide have no interest in knowing that you'll be on vacation until the 12th of next month, and especially don't care to be reminded of it again after every message they send to the list.