You want a cool Porsche poster? How about one of your own Porsche?
This is one of the coolest things I've seen on the net. Forgive the weird name, but it's called "The Rasterbator."
It creates a rasterized image of your photos. Essentially, what you do is upload a photo and it spits back a .pdf file that you print out. The pages all line up to form one large image. It looks cool visually because each print out is nothing but large dots (relative to pixels anyway). From close it's hard to make out what it is, but step back and you see the image.
It's free.
Here's the link:
http://homokaasu.org/rasterbator/
Play with it for a while and mess with the settings.
Here's my example:
I took it a step further and put each printed out sheet in a cheap Wal Mart frame to class it up a bit. (A tip: if you're gonna get frames, don't make the image print on more than 15 sheets of paper, it can get large [and expensive])