I have read somewhere that certain protocols like Telnet allow you to keep sending an ever-increasing amount of data (that the server itself does not need to keep around) without the response ever ‘ending’ (but importantly also without it ever timing out), allowing you to make the connection of an attacker hang.
Not only will this prevent them from hacking you, you will also be providing a service for the internet as a whole by trapping an attacker.
Unfortunately I cannot find this particular project at this time, although many similar Honeypots exist.