Every now and then I get contacted by creationists, erm, sorry, "adherents of Intelligent Design theory" (e.g., like the comments to this post). They invariably come up with the usual improbability argument: how this or that couldn't possibly have evolved. For one, most of the examples these persons give have already been explained and we know pretty well how these traits (e.g. the eye) have evolved. For those not yet known, we'll just have to wait until further research enables us to understand their evolution. Indeed, it appears to me, we know today a lot more about the machanisms of evolution than we know about the mechanism of gravity. Yet nobody seriously advocates "intelligent falling".
Normally, you'd think this alone should end the debate. But of course, for creationsts, eh, IDers, their position is a matter of belief and not of evidence. And who am I to attempt to use evidence and reason to argue against belief? That obviously would be so Quixotesque!
So better not to argue with their belief - after all, we're all free to believe what we will, aren't we? However, there are good reasons to doubt the validity of the idea that this "design" is really all that intelligent. Surely, the natural world, the universe and everything is marvelous, but it also contains a huge number of design flaws, which would make anybody think twice about calling a hypothetical designer "intelligent". My favorite examples are the esophagus/trachea design (why would you connect them? So that people choke and die on a piece of food? How intelligent is that?), the knee design (if you were to design a knee that ruptures the most crucial ligament with one false move, you'd face serious litigation!) and the design of the vertebrate column (if you were to build a tower, would you put the carrying structure in the center or at one end of it?). Prompted by a recent article in The Scientist, where the author describes the less-than-intelligent design of a butterfly parasite, I went of and searched for a few more examples. I found the "Unintelligent Design Netork (UDN)", which emphasizes that 99% of all species are extinct - how intelligent is a designer whose products fail 99% of the time? There's a book called "Unintelligent Design" by Robyn Williams, with a lot of good questions, like:

Which ties in nicely with my favorites
The New York Times also has some great examples of less-than-intelligent design:


With such a wealth of evidence against the intelligence of the creator, err, designer, you must surely follow Richard Dawkins when he wonders "Just what kind of designer designed such a designer"?
Maybe the designer really is/was nothing more than a monstrous lump of Spaghetti and Meatballs...