From a command prompt pressing tab will auto complete a file name or folder. For example:
C:\>cd win (TAB) becomes cd windows
C:\WINDOWS>cd sys (TAB) becomes cd system32
C:\WINDOWS\SYSTEM32>cmd (TAB) becomes cmd.exe
Continuing to press tab cycles through all other files matching the pattern.
This Command Prompt functionality has been around since Windows 2k and it's still available in Vista. I don't believe it's particularly well known and can be useful. Rather than just cycling through previous commands using the cursor keys, a list of the previous commands can be recalled by pressing F7. Select the required command using the cursor keys and hit enter to execute.
