My first real job out of college was at IBM in Boca Raton, Florida where the original IBM PC was made. It's been long closed, but I remember my boss had a framed picture of Thomas Watson sitting under the Think sign hanging on the wall that I thought was really cool. I just like the idea of that simple word as a mantra: Think. It's clear, focused and yet says so much.
IBM has embraced the Think theme again with a new set of ads and mini-site at http://www.ibm.com/think, and I think it's great. There's little idea or 'light-bulb' marks around a bunch of different symbols focused on a "smarter planet". Very neat idea. I love flexible logos like that (like in the background patterns of ovi.com as well).
Did you know that think.com is the third oldest .com domain name? It's owned by Oracle now, which is odd considering the association I have in my mind between IBM and the word. Personally I think that domain is right up there with hello.com as my all-time 'kill or die for' domain names. (Obviously whoever registered it 25 years ago probably felt the same way. Think about how many thousands of times since someone has tried that domain in a search engine, only to be turned down... :-) ).