Stash is an extension that lets you save your favorite links to your phone directly from any app, in a list only you can see. Keep track of pictures, videos, links you find or items you want.
MailTumble is a service that tokenises email addresses, allowing you to share your lists with third parties. Like a URL shortener, MailTumble lets you program in contractual obligations for emails and email lists.
LinkVault is an app that helps you to save links from different apps in a centralized place so that you don't have to maintain part of your collections on multiple apps. It also provides functionality to tag and search links easily.