For example, a facebook explication with 100k monthly users, are they worth anything if so where can they be sold? the application is a simple calculator.

The Net-Worth of a FB Application depends on MUA (Montly Active Users). I will give you a simple mathematical way to calculate the actual net-worth based on income stats. I have a quiz application which has 2 million monthly active users. On an average each user sees 5 pages for saying yes or no in the quizzes. There are 3 ads on each page so 2,000,0000 x 5 x 3 = 30 million monthly impressions. Divide that by 1k which is CPM. Iam getting 0.5$ CPM payrate from rockyou ads. That gives you 30k x .50 = $15k per month. This income stats is from a real application, you can calculate and do your own math keeping this in mind.

Great, thanks this gives a clear monetization method for facebook applications and how they can become very profitable. As far as selling un monitized aplications, is that against the TOs?

Iam surprised how you did that, since google adsense is not in the allowed list of ad providers for FB apps.

I know it's not allowed to use it, but I have a very gr8 method to use it with 0.1% of Risk I used it for more than year, and after the previous FB changes about Ad Providers, Facebook approve all apps I submit with Adsense PM