Standalone addon that will automatically link loot in raid chat or raid warning (depending on whether or not you can speak in raid warning).
Commands:
/autoloot threshold <amount>
/autoloot delay <amount>
The threshold is the item quality threshold. 0 is basically all items, 1 is whites, 2 is greens, 3 is blues, 4 is epics, 5 is legendaries, 6 is artifacts (i.e heirlooms). Its default value is 4, so that only epic items will be linked.
The delay is the amount of time between consecutive linkings of a given item. It's basically there to prevent you from opening up boss's loot, accidentally closing it and then opening it again, linking all items twice. Set this to whatever you want, its default value is 5 seconds.