I have been using pintrest online for a couple of months. It has been a great place for me to find new recipes and craft projects. It also allows you to link up with friends via Facebook and share common interests with those that you are friends with. The concept is that each user has multiple bulletin boards where they can "pin" ideas on it, almost as though it was a virtual cork board that all friends and users can see.
It is always fun to see who "likes" or "repins" something I have posted on there. I have also been able to get new ideas for cocktail parties of BBQs via keyword searches. Also, i have been able to create a "my style" board which allows me to find outfit ideas and express who I am as an individual to my other friends.
There is also a iPhone app that allows me to search and browse on the go and see what my other friends are pinning. Great way to kill time while standing in line someplace.
The only downside is i wish there was a way to search better. Sometimes keyword searches are too general and there it can become difficult to filter through them. Other than that, it is a great new concept for a website where Facebook has become to commercialized.