Original developed for Windows Mobile nearly 10 years ago. Booksync allows you to match contacts in your phone with friends on Facebook and then update your phone contact with your friends picture.
One thing to note
Facebook changed their API so you can only get a list of friends that are also using the same application. Back in the day they would just give you access to the full list but those days are over which basically makes this useless.
This was the first application whilst learning Xamarin Forms using Visual Studio for Mac so it's a little rough around the edges.