For those of us who had a tea party in Booty Bay you know that goblins around the world hate us for resisting their trade embargo. But what do you do once you have your vaulted Admiral's hat and title? Well you need that rep with the goblins to go back up so you can buy from OPEC again.

There are several ways to gain this rep back:
Quests:
http://www.wowhead.com/?quest=9259 - Gives 500 rep to Booty Bay, and 250 to the rest.
http://www.wowhead.com/?quest=9268 - Gives 500 rep to Gadgetzan, and 250 to the rest.
http://www.wowhead.com/?quest=9266 - Gives 500 rep to Everlook, and 250 to the rest.
http://www.wowhead.com/?quest=9267 - Gives 500 rep to Ratchet, and 250 to the rest.

Note that you will lose 500 rep with the Bloodsail Buccaneers after each turn-in.

Quests that don't make you lose pirate rep:
http://www.wowhead.com/?quest=5518
http://www.wowhead.com/?quest=5525
http://www.wowhead.com/?quest=7003
http://www.wowhead.com/?quest=7725

Finally there are mobs that you can kill:
Venture company NPCs! Here are some locations:
http://www.wowhead.com/?npc=675
http://www.wowhead.com/?npc=1094
http://www.wowhead.com/?npc=921

These are not confirmed but they should provide varying levels of mobs that work:
http://www.wowhead.com/?search=venture#npcs:0+3+1

Also these guys give rep without hurting pirate rep... even though they are pirates:
http://www.wowhead.com/?npcs&filter=na= ... =440;crv=0