Steam Card Inventory Valuation
Steam has a trading card system where you can get cards for games you own by playing them. These cards can be bought and sold player-to-player on Steam's Community Market. Near when this system was first introduced, I wrote this script that would fetch current values for all the cards in your inventory from the Community Market and show you the sum total value of your card inventory. I assume it probably doesn't work anymore, given that the Community Market has seen substantial redesigns since.