Occasionally, when I report spam I wish I could send a short message to the cnuts that spam, say, twitter size, that way I could have some fun with them and those who carry them.

Hi, Bruce,
...If only! If it were possible to get a message back to the true originator of the spam, it might even be feasible to grab 'em and take 'em to court for electronic trespass (assuming there are legal jurisdictions where such action can be taken and has a chance of winning) or even ask the national authorities to pay them a visit. Unfortunately, most spam is sent by spam bots in botnets these days, so the true originator of the spam is well hidden. Those who carry them are a different matter -- SpamCop sends complaints, by your direction (when you report), to the abuse e-mail address(es) of the source (IP address [the IP address of the spambot, if it indeed came from such a source]) of the spam.

As Steve says, limited/no opportunity with the current 'mainstream' annoyances, getting to grips with a botnet is a specialist proposition and even the experts have very limited success. 419-ers are a different proposition though - search the internet with a phrase like fun with spammers for inspiration. But be very careful, they are criminals, they really want to know who you are and they (the successful ones) know their own craft.