This one's a bit nerdier, so you may not have seen this or heard of this company. But chances are, you would've seen one of the logos of one of their products -
Java. You know, the coffee cup logo you see on your phone and on some websites.
What I like about this logo is the fact that their logo (i.e. the picture bit on the left) reads s-u-n from all directions. No matter how you turn the logo, you can read Sun from it. It isn't as hidden as the FedEx one, but still cool in its own right. Shows not only ingenuity (through the ingenious design of the logo), but also that the company looks at things from all directions. There's probably other meanings too, making the logo itself a deep meaningful object, representative of the company.
Lastly this is one that again you probably wouldn't have heard of either.
CLP, or China Light & Power, is the dominant power company in HK, and China now. But again, while you haven't heard of CLP, you would've heard of their Australian business,
TRUenergy (I was surprised to discover this - they completely own the Yallourn power station in Victoria, plus have interests in some of our wind farms).
This logo is cool in a similar way to the Sun one above - they've incorporated the company name in their logo in a smart way. The logo, being the circle bit, consists of a C on the left, L in the middle, and P on the right with the downstroke combined with the L. You won't know this unless you know Chinese, but the letters are placed like that such that it forms the Chinese character representing Chinese,
中 (zhong in pinyin). For example, China is 中国 (zhong guo), which could be translated as 'Chinese nation' (please correct me if I'm wrong - my Chinese is a bit flaky ever since year 12 finished unfortunately...).
Logos are such an important marketing tool - in most cases it is what people first identify with when they see your company. Having a well thought out one becomes great advertising for your company as many consumers, consciously or not, do notice these things. It's just like using the right type face for your company title - something in Times New Roman style will convey different messages than something in Arial.
Check out this free ebook from Before & After magazine for more ideas on designing logos with letters.