Suggestion: Delete this thread and drop the idea. It's useless and only makes bitcointalk look even more like a joke. It was bad enough to snap the ripplelab-domains and start trying to sell them.
Want a little more info about my suggestion?
... Sure but first tell me how you would distribute the stamps used to make spamming the network harder/expensive. Actually there's one alternative way - that is to give people these stamps depending on their bitcoin stashes - but that's not very good after all.
Are you aware that network spamming was never a problem with the classic ripple pay?
Do you understand that the network would be spammed without some kind of fees to pay?
Then why has it never happened for ripplepay? Why am I not paying a fee to download or upload Ubuntu ISO? Why am I not paying a fee to access this page and submit a post?
Transaction fees exist in BTC to provide an incentive for mining. It is not needed in Ripple. It was added to create an artificial demand for XRPs.
It's easy to avoid spam if you never leave obscurity.