Stumbled across the today and an article on clever logo designs. Now we've just had to make a few logos in recent weeks and you always know how bad certain logos look, many have aged badly or have no meaning with what they should be selling and it does annoy me far too often if we have to deal with them on a design brief. So here's a couple of great ones on this blog to get you started.
The Australia shape created by her leg and arm.
The arrow in the E and X.

His article is more explanatory.