Uses for excess legendary and set items?

If you are playing patch 2.3 or later you can extract the legendary powers in kanais cube. http://www.diablowiki.net/Legendary_affixes

If you are playing 2.4 or later you might want to keep the set items to do the set dungeons. http://us.battle.net/d3/en/blog/19941042/patch-240-ptr-patch-notes-12-14-2015

Otherwise just salvage the ones you don't use.

Yep, salvaging unwanted legendary and set items will yield 'Forgotten Souls' which are handy for use in Kanai's Cube. Don't forget you can strip the legendary power from them in the cube, so if you haven't already, strip the powers of any you don't want. There is an achievement for doing this.

As they can be used to upgrade rare items to legendaries, re-roll items and other useful things. They'll also be required to re-roll stats on legendary and set items at the mystic.

In the cube, these recipes require souls.

• Reforge Legendary Item
• Convert Set Item