How does lending / leasing in NXT work? What are some use case scenarios? Since you can lend / lease you nxt to another account. 

What are the pros/cons of this nxt lending feature? 

What are some use case scenarios?
Leasing gives the other account your forging power, without giving them the ability to spend your coins. The two main use cases are:


To lease to a forging pool run by someone else. This avoids the need for you to run a server 24/7, and the pool should forge more often, smoothing out the peaks and troughs in forging income.
To lease to a forging node run by yourself, but on a machine you don't trust; for example a cloud service. You keep your balance on a secure machine and lease it to the insecure one.