What are some alternatives?
When comparing Imvges and Diigo, you can also consider the following products
Pinterest - Pinterest is a visual discovery tool that you can use to find ideas for all your projects and interests.
Pocket - When you find something you want to view later, put it in Pocket.
weheartit.com - We Heart It lets you create an online album (a heart) with your favorite images and videos.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Pinry - Pinry is a private, self-hosted, Pinterest inspired by Wookmark and built on top of Django.
Pinboard - Pinboard is a personal archive for things you find online and don't want to forget.