Mac OS X Keyboard Shortcuts - 10.5

http://support.apple.com/kb/ht1343

Mac OS X - reset password - 10.5+ (no boot disk)

This description is from: 

http://support.apple.com/kb/TS1543?viewlocale=en_US

1. Restart in Single User mode (hold Command-S during startup). Note that single-user mode always uses the US English keyboard layout.
2. At the prompt, type this followed by Return: mount -uw /
3. Type this:
   launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist

5. Press Return
6. Type this, then press Return: ls /Users
7. Look at the listing and note the short name (username) of the affected user account.
8. Type this:
   
   dscl . -delete /Users/username AuthenticationAuthority
   
   Note: Replace "username" with the affected user account's short name you noted above.
9. Press Return
10. Type this, followed by Return: passwd username
    
    Note: Replace "username" with the affected user account's short name you noted above.
11. At the "New password:" prompt, type the user's password, then Return. Note: It is recommended that the original user's password be used to match the keychain password.
12. At the "Retype new password" prompt, type the same password, followed by Return.
13. Type this, followed by Return: reboot