This addon keeps your friendslist synchronized for all characters. So if you add/remove friends on one character they will automatically be added/removed to other characters you sign on to. You can disable the automatic synchronizing and either enable it for only some characters or just synchronize manually.

Since all the friendssharing addons I tested (4 or 5) were really buggy and didn't work properly I decided to make my own instead. And then I figured, why not release it so you don't have to? So here it is