This is a card I created out of the frustation you feel when you have only one coin and you have to forfeit your turn, or when you have two buys but you are left with only one coin for the second one.
It costs only 1€, so you can actually buy something if you have a spare coin (well, you could always buy a Copper or a Curse, but almost nobody does).
Name: Rat
Type: Action-Victory
Cost: 1€
Text: +1 card
+1 coin
1/2 VP
Rat in Catalan means mean, stingy, miserly or scrooge, as this can be related to both the cost of the card an the power it gives to you: one more card, one more coin and half a victory point!
I like this card and I never hesitate to buy it whenever I have a spare coin in hand, I think it pays off, despite its poor look at a first glance.