Donation system

I am considering adding some kind of donation system that has perks (such as no ads) for members who donated certain amount.

Any suggestions on how to do that? Is there a third party addon that simplifies the process?

Thanks for the reply.

How do the users make the payment though? I don't think the forum has any built in payment system.

Do users make payment via third party service like PayPal then admin manually add the user to the donor user group?