Pinterest is often compared to Googles Image Search, but while Google is a simple image search and requires you to dowload the images to your device, Pinterest allows to collect ideas ("pins") in so-called "boards". This can be single images or links to websites.
Pinterest is an excellent tool for creatives to collaborate on projects and share ideas. Just create a board, invite all collaborators and start collecting ideas.
Pinterest boards can be public (so the board and its pins are visible to everybody) or private: the board, it's pins and notes are only visible for the creator of the board and invited collaborators
I use Pinterest for most of my projects for planning and as a mood board.