I think of Pinterest as a graphical representation of my virtual bookmarks.
According to Pinterest:
Pinterest is a virtual pinboard. Pinterest allows you to organize and share all the beautiful things you find on the web. You can browse pinboards created by other people to discover new things and get inspiration from people who share your interests.
People use pinboards to plan their weddings, decorate their homes, and share their favorite recipes.
I like that instead of bookmarking a site, and only having a sometimes badly named link as my only reference, now I can see the lovely little image of whatever it is that inspired me -- craft, recipe, decor, etc.
Some claim it's a time waster. I don't know. No more a time waster than anything else online! *LOL* Also, I think it can be helpful when thinking about, say, what your decorator style is. Maybe you don't know, but it you start pinning everything you like on one board, then you'll eventually get to see a pattern.
So, if you want to,
And, if you need an invite, let me know! ^_^