Just a note about subscribing...
I can either subscribe for $20 and let it be a recurring payment or pay $10 donation to the kitty once.
I would easily have paid $20, but I didn't like the idea of it recurring.
Since I couldn't donate $20+ and get a one time payment, the site lost money. I was afraid that if I donated twice so close together that paypal would flag it.
It would also be highly preferable if the user had a way to know which way they had paid, perhaps in the email notification.