According to The Economist:

Money has three main qualities:

  1. as a medium of exchange, buyers can give it to sellers to pay for goods and services; 
  2. as a unit of account, it can be used to add up apples and oranges in some common value;
  3. as a store of value, it can be used to transfer purchasing power into the future.

Can time be a medium of exchange? I guess sort of, but it's a little like barter for services. Much better to use money for that.

I guess it can be used as a unit of account. It took me as long to write this as it takes me to fold my laundry and clean my room. Learning French to conversational levels might take as much time as playing through Arkham Asylum and the next Assassin's Creed. Useful things to know.

Turns out you can't store time though. Those few minutes of spare time you have can't be put into a time bank and then redeemed for extra spare time in the future. It goes stale very quickly.