Which Utilities am I likely to use?
You'll most likely use only a few of the utilities within the Utilities folder.  These are the most commonly used utilities:

• Activity Monitor
• AirPort Utility
• Boot Camp Assistant
• Disk Utility
• Exposé
  
• Migration Assistant
• Spaces
  
• System Profiler
• Terminal
  

Although other utilities exists (such as Network Utility, ODBC Administrator, RAID Utility, and X11), if you are not a network administrator or one who wants to get into the underlying UNIX architecture of Mac OS X you probably won't need to use these utilities.

Just navigate to the Utilities folder to see the different utilities that are available.

Updates

• April 6, 2010 - Content revision, added links to specific Utilities