Okay, my first post, woohoo.
Anyways, semi useless, but works for trinkets, temp buffs, etc. I use it with my Orb of the Sindorei.
Basically.
You're about to log out for the night, for a while, etc, simply use your trinket/buff. You'll gain the effect/buff, and when you log out the spell/item timer resets but the buff timer does not.
Common knowledge for some, not for others.
Honestly, at the moment I cannot think of a spell/use this has other than extending trinkets which give you a form for a duration then logging out.
-Shrug-