When you start Regedit, it automatically opens the last key that was viewed. (Registry Editor in Windows XP saves the last viewed registry key in a separate location). If you wish to jump to a particular registry key directly without navigating the paths manually, you may use any of these methods / tools.
Using a VBScript: Copy these lines to a Notepad document as save as registry.vbs
'Launches Registry Editor with the chosen branch open automatically
'Author : Ramesh Srinivasan
Set WshShell = CreateObject("WScript.Shell")
MyKey = Inputbox("Type the Registry path")
MyKey = "My Computer\" & MyKey
WshShell.Run "regedit", 1,True
Set WshShell = Nothing
Double-click Registry.vbs and then type the full registry path which you want to open. [ Example: HKEY_CLASSES_ROOT\.MP3 ]
Limitation: The above method does not help if Regedit is already open.
Regjump from Sysinternals.com
This little command-line applet takes a registry path and makes Regedit open to that path. It accepts root keys in standard (e.g. HKEY_LOCAL_MACHINE) and abbreviated form (e.g. HKLM).
Usage: regjump [path]
Example: C:\Regjump HKEY_CLASSES_ROOT\.mp3
12Ghosts JumpReg from 12ghosts.com
Jump to registry keys from a tray icon! This is a surprisingly useful tool. You can manage and directly jump to frequently accessed registry keys. Unlimited list size, jump to keys and values, get current key with one click, jump to key in clipboard, jump to same in key in HKCU or HKLM. Manage and sort keys with comments in an easy-to-use tray icon menu. Create shortcuts for registry keys.
To Jump to Registry key from Internet Explorer / Firefox, use my menu extension here:
Add "Go To Registry Key" to the Right-Click Menu in Internet Explorer