From Amazon's Kindle 2 help pages:
To cancel an active subscription:
1. Visit the Manage Your Kindle Subscriptions page.
2. Locate the subscription you wish to cancel in the active subscriptions section and click the "Cancel Subscription" link.
3. Click the "Cancel subscription" button in the popup window to confirm your choice.
Once you cancel a subscription, you will stop receiving new issues immediately and you will no longer be able to re-download back issues, and a refund for the remaining balance of your subscription will be issued if applicable.
Has anyone ever tried this? I've sent an e-mail through the contact us button (I hope they'll contact me

), basically I wish to cancel a subscription to a newspaper, but obviously, if it means that I will lose the whole month's price (because it's immediately terminated) I'll stick with that and unsubscribe later.