One cool addition to Lion, at least from a techie's perspective is System Information (previously known as System Profiler). On the outside it looks pretty much like System Profiler, with all it's categories:
… but, hit Cmd-I and voila:
Notice the title of the window. I'm guessing this will one day replace the venerable “About This Mac” under the Apple menu. This thing could be pretty useful since it tells you how you're hard drive space is distributed:
… and about the current and possible configurations of RAM:
The “Support” and “Service” tabs hold some useful links but unfortunately they all seem to go to blank pages at the moment.