As cool as Spotlight is, not all of us need it clogging up our menu bars. Apple doesn't let you Command-drag it out of the menu bar like you can other extras, but you can still remove with a bit of hacking.
- As an administrator, navigate to /System/Library/CoreServices, and delete Search.bundle. If you think might want to re-enable it later, just move it somewhere else or rename it.
- Open up the Activity Monitor and force quit SystemUIServer. When it reopens, your menu bar will be Spotlight free.
[robg adds: I tested this one, and it does indeed work. I used the terminal to just move the file (sudo mv Search.bundle Search_SAFE.bundle), and then restarted the SystemUIServer. Sure enough, the icon was gone. But in case it's not obvious from the hint, Spotlight's functionality is also gone -- you can't use Command-Space or Command-Option-Space. Spotlight still works in the various Spotlight-enabled applications, but you can't use its system-wide functionality. To put things back to normal, I just reversed the sudo mv and restarted the SystemUIServer again.]

