High road, matt. Just be glad he’s gone.
On the practical level, you know any hijinks done with them have the potential to reintroduce said fucker into your life.
Serious advice: be the better man. Destroy them.
Semi-serious advice: be the smarter man. Don’t publicize them, but keep them around as a potential bargaining chip should wanker-boy come back.
Fun advice: be the happier man. I like the Stile Project and T-Shirts ideas.
Unfortunately, our world does not work that way.
Send him a letter. Let him know you have his naked pictures. He might want to have them back for a price.
Post them to www.consumptionjunction.com
Prior to answering such a serious question, I feel I must examine the photos.
My e-mail address is in my profile. 
Kazaa.
UR is right on - if he ripped off your roommate, let your roommate get his money back.
True this is blackmail, and therefore I belive illegal, but it certainly seems fair in this case…
Matt,
Before you send them out, if you’re REALLY mad, alter them in photoshop. Shrink things. :eek:
[sub] spoken like someone who has never had any pictures of that area ever taken. [/sub]
Another vote for sending it to his parents. Just to cover your bases, box it up with the rest of his stuff that can be easily shipped and when he calls, threatening to burn your house down, just claim you were being considerate.
He may not care. I know if you found three naked pictures of me, I really wouldn’t care what you did with them. Post them on the Internet, send them to my Mommy; go ahead.
I’m with the advice that you put all his stuff in a box, but don’t send it anywhere. Just save it. Let him ask for it. Don’t spend your money to ship it.
I doubt he will come back for the stuff, considering he ripped off your roomate. When you move you can decide if you want to send it, or toss it.
You can be the better man and mess with his head.
Make photocopies of the pictures in question. Make sure it’s obvious they’re just photocopies. Destroy the actual photos.
Then give him the photocopies and say, “I found these in your stuff. I assume you want them. …What? Originals? No, all I have are these. Do you think maybe somebody else has the actual photos?”
Then he sweats for the rest of his life, and you’re off the hook.
Well, I have nude pictures of my evil ex housemate, that I own. They were taken (with her consent) with my camera and I developed them. So far I keep them filed away, smiling at the thought that she knows that I have them and I never throw photos away. Make sure he knows you have them and just keep them safe.
I would not suggest such a thing. Not me. All I was saying that a satisfactory arrangement can be reached with regards to the photos and the money.
Cervaise wins.
Simply beautiful.
You could always post them at one of those rate your wang sites or something. More fun if you go to the site and repeatedly vote for a low score under different names while leaving cruel messages then send him the link. 
Just curious, matt: In what way were they “interesting”, besides being nude shots? (You don’t have to answer.)
I’d go with Flashpaper’s suggestion. Cliff would know what to do with them.
Fascinating question, otherwise. I don’t know what I’d do in this case. Probably box it all up and put it away. But I’d feel very very tempted to do something with them.