Couldn't find this posted here yet, and with a recent post about a hearthstone trick, I thought I might as well.
Not sure if this is common knowledge, but this has gotten me out of a few jams. For those who don't know already
The Scenario: You're farming some instance way out in the middle of nowhere, it's a long time before your hearth will cool down, and don't really feel like walking to the nearest gryphon.
Solution:
While still in the instance, invite someone to your party (whether it is a random person or a friend).
Promote them to leader.
Leave the party.
Wait for the 60 second port timer to diminish.
Viola, a free hearth even when your hearthstone is still on cool down.