The things you can collect and organize are endless: recipes, fashion, hair and makeup tutorials, photography, travel, exercise, crafts and design are just beginning examples what others are pinning on Pinterest.
Pinterest is also a great way to promote your own website or blog. It has become a top traffic driver. You can sign up via your existing Facebook or Twitter accounts, and share you pins on those social networks. You repin existing Pinterest content, or you can pin original content that you find online. I prefer the browser interface on my laptop, but when I'm out and about the Android App is great!
The Pinterest app for Android (and iOS) is free.