My bank allows me to create temporary credit card numbers. I can specify the amount of money that can be charged on it as well as the expiration date.
I've used these when traveling so I wouldn't have to enter my real credit card number on a website in some random internet cafe.
There are some subscription-based services with free trials that I'd like to try out, but knowing myself I'll never remember to cancel them in time to avoid being charged. So I thought I could create a temporary number (say with 50 cents on the "card") to sign up with, and then if I forget to cancel, no big deal.
Is there any "trouble" one can get into by doing this? Any other downside that I'm not thinking of?