There is a lot of discussion lately about Facebook, its API, its valuation, its growth prospects, and so on. Lately, I realized that Facebook has a very nice functionality: it is a ... facebook! What do I mean?
I have had a Facebook profile since late 2004. While I have a full profile, I am not that active, since I tend to reach most of my contacts either through email or through instant messaging. Nevertheless, every years students who take my undergrad class, add me as a "friend" on Facebook, and these contacts remain even after the class is over.
Now, as my freshmen students in 2004 reach their senior year, they start asking for recommendation letters. Remembering who is the person who asks for a recommendation, just by looking at the name, tends to be tricky: Each year we deal with hundreds of students, and unfortunately our human memories are not keeping up with Moore's law. However, when the student is on Facebook then I can check easily the corresponding Facebook profile. By looking at the photo of the student, I can remember very easily the student, the performance in class, and the general impression that I had formed during the course. Then, checking the grades in the homeworks and projects completes the image, and writing a recommendation letter tends to be much much easier.