But if this goes on any "permanent" material (eg. printed on posters and such), it's nasty that the link would be on a domain controlled by someone else. Someone whose business model could change at any time, who could shut down and the links wouldn't work, or worse, who could start redirecting to malware.

My advice: Decentralize this by offering it not just as a service, but by licensing it to companies that want this on their own servers. I suspect some would pay a decent price for this.

Either that, or open source it. :)