As for users, the latest official number we can find clocks in at 845 million active monthly users, which comes directly from Facebook’s IPO filing. Interestingly, 850 million users has also been widely reported.
To stay conservative, we’ll go with $102.8 billion / 845 million users. This means each user is worth… approximately $121.
Though this is all for fun and games, it’s perhaps telling as well. Every Facebook user adds up to the gigantic social platform we see today, and while the sum is likely greater than the parts, there’s no reason to discount the value of a user.