+1 for Quicksilver (adding key bindings to all of your applications and some of there core functionalities definitely supports the 'power user' tag) - and I agree that most of these are just preferred apps, not necessarily power user-specific.
Text edit is the other app that gets replaced, BBEdit or UltraEdit for any efforts that just aren't comfortable in vim. I would hesitate to call adding a GUI text editor a 'power user' update, though.
The rest of this reads like an ad for the various services (many of which are good, but not indicative of a 'power user').
How can people live without making use of spaces?
Yes, Quicksilver is a great replacement for Spotlight Search. It indexes very fast, and it is very powerful for mundane and time consuming tasks such as moving files from one folder to another, or quickly compressing and email files. All can be achieved at lightning fast speeds with just a few keystrokes. I almost always launch apps with Quicksilver.
