Here's an amusing hobby:
1. Start Amazon EC2 instances (or any other cloud service)
2. Use something like honeyd to listen on all ports
3. Wait for random activity associated with the previous owner of the EC2 instance to start flowing in.<p>I stumbled across this by accident after getting flooded by connections from apps.facebook.com which seems to be trying to interact with a Facebook app that was previously hosted on an IP which I'm now using. Presumably the previous owner of an EC2 instance had a DNS name that resolved to this IP and didn't see the risks of doing so. Remember: the Amazon public IPs are <i>temporary</i> and will be reassigned once the EC2 instance stops or dies.<p>For the sake of your users' privacy and security, <i>use Elastic IPs</i>. Even if the instance dies, the Elastic IP still belongs to you and won't be accidentally be reassigned to someone else. When you start up a new instance you can have the Elastic IP assigned to the new instance using ec2-associate-address.
Am I the only one who get's frustrated by 'considered harmful' titles? Sorry for being off topic.<p>EDIT: I'll give you that it's not as bad as the whole (win|fail|this) thing that's becoming popular.
For the sake of your users' privacy and security, use TLS (or IPSec) and a certificate that identifies your server. Anything sent in the clear is vulnerable to eavesdropping and tampering, whether or not the destination IPv4 address appears to be under your control.
You should make a web site with examples or a report of the kinds of traffic you get. I'd do it, and get a zillion hits on it and probably some press attention, but it's your idea.<p>You have a really good point.
I still get requests to my dedicated server at Softlayer for the Facebook app which used it before me. I've had the server since mid-2008. Really, this seems like a problem on Facebook's side.<p>The bigger problem is trying to run a mail server on EC2. You can't, really, as a lot of providers are still doing (stupid) IP based filtering.