Thought it would be a good idea for people to post their favourite registry tweaks. I'll get the ball rolling: (Make sure you explain what it does 
)
AVI scanning disable
Problem:
Windows scanning avi files and using 100% CPU and lagging system when viewing folders with large numbers of avi files.
Solution:
Delete the 'InProcServer32' folder from the following location:
" HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{87D62D9
4-71B3-4b9a-9489-5FE6850DC73E}\InProcServer32"
What it does:
This will prevent Explorer from loading shmedia.dll in response to file property queries on these files. This will not effect your ability to play files, get file attributes, or even view thumbnails.
Removing shortcut arrow Icon
Problem:
Shortcuts have an ugly white box with a black arrow in the bottom left corner.
Solution:
Delete the value named 'IsShortCut' from the keys:
[HKEY_CLASSES_ROOT\lnkfile],
[HKEY_CLASSES_ROOT\piffile],
and [HKEY_CLASSES_ROOT\InternetShortcut].
What it does:
Simply removes the small shortcut icon.
Dr Watson Disable
Problem:
I never use Dr Watson so rather than waste clock cycles and Hd space I want too disable it.
Solution:
Change the auto field to 0 to disable it. If you want it back on later just change it back to 1. (see location below)
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug
What it does:
Turns Off Dr Watson
Nero Scout Removal
Problem:
Not a problem I have as I use the much better RecordNowMAX & Prassi's ONES but friends have said how annoying Nero Scout is so I dug this tweak out to get rid of it.
Solution:
Paste the following into the Run dialog box and press return:
regsvr32 /u "C:\Program Files\Common Files\Ahead\Lib\MediaLibraryNSE.dll"
(Obviously edit the bold part above to where you have the 'MediaLibraryNSE.dll' installed if it's not at default.
What it does:
Removes Nero 7's Nero Scout from 'My Computer'
Adobe PDF maker Toolbar Removal
Problem:
Adobe seem to think that their PDF maker is Soooo important that we should lose a massive amount of useable screen area for it and not be able to decide if we want to remove it
Solution:
Open a RUN or DOS window and type:
regsvr32 /u "C:\Program Files\Adobe\Acrobat 7.0\PDFMaker\Office\pdfmofficeaddin.dll"
This one sorts outlook's toolbar out:
regsvr32 /u "C:\Program Files\Adobe\Acrobat 7.0\PDFMaker\Mail\Outlook\PDFMOutlook.dll"
(Again if your not using default install directorys make sure you edit the bold parts above so that it points to the relevant dll's
What it does:
Removes the annoying Adobe PDF toolbar
Open folder in new window
Problem:
I have always wanted to be able to right click a folder and select open in new window.
Solution:
Copy the below text and paste it into notepad and then save it as 'rightclickreg.reg (the bold bit is the most important you can label it whatever you want before that, also again if like me you don't have you default programs install folder on C: then edit the bold bit below so that it is directed correctly)
Once saved simply double click the .reg file for it too make the changes to the registry
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Folder\shell\Open In New Window]
[HKEY_CLASSES_ROOT\Folder\shell\Open In New Window\command]
@="C:\\Program Files\\Internet Explorer\\IEXPLORE.EXE \"%1\""
Thats the ball rolling, now lets see what other little gems we can come up with.
)AVI scanning disable
Problem:
Windows scanning avi files and using 100% CPU and lagging system when viewing folders with large numbers of avi files.
Solution:
Delete the 'InProcServer32' folder from the following location:
" HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{87D62D9
4-71B3-4b9a-9489-5FE6850DC73E}\InProcServer32"
What it does:
This will prevent Explorer from loading shmedia.dll in response to file property queries on these files. This will not effect your ability to play files, get file attributes, or even view thumbnails.
Removing shortcut arrow Icon
Problem:
Shortcuts have an ugly white box with a black arrow in the bottom left corner.
Solution:
Delete the value named 'IsShortCut' from the keys:
[HKEY_CLASSES_ROOT\lnkfile],
[HKEY_CLASSES_ROOT\piffile],
and [HKEY_CLASSES_ROOT\InternetShortcut].
What it does:
Simply removes the small shortcut icon.
Dr Watson Disable
Problem:
I never use Dr Watson so rather than waste clock cycles and Hd space I want too disable it.
Solution:
Change the auto field to 0 to disable it. If you want it back on later just change it back to 1. (see location below)
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug
What it does:
Turns Off Dr Watson
Nero Scout Removal
Problem:
Not a problem I have as I use the much better RecordNowMAX & Prassi's ONES but friends have said how annoying Nero Scout is so I dug this tweak out to get rid of it.
Solution:
Paste the following into the Run dialog box and press return:
regsvr32 /u "C:\Program Files\Common Files\Ahead\Lib\MediaLibraryNSE.dll"
(Obviously edit the bold part above to where you have the 'MediaLibraryNSE.dll' installed if it's not at default.
What it does:
Removes Nero 7's Nero Scout from 'My Computer'
Adobe PDF maker Toolbar Removal
Problem:
Adobe seem to think that their PDF maker is Soooo important that we should lose a massive amount of useable screen area for it and not be able to decide if we want to remove it
Solution:
Open a RUN or DOS window and type:
regsvr32 /u "C:\Program Files\Adobe\Acrobat 7.0\PDFMaker\Office\pdfmofficeaddin.dll"
This one sorts outlook's toolbar out:
regsvr32 /u "C:\Program Files\Adobe\Acrobat 7.0\PDFMaker\Mail\Outlook\PDFMOutlook.dll"
(Again if your not using default install directorys make sure you edit the bold parts above so that it points to the relevant dll's
What it does:
Removes the annoying Adobe PDF toolbar
Open folder in new window
Problem:
I have always wanted to be able to right click a folder and select open in new window.
Solution:
Copy the below text and paste it into notepad and then save it as 'rightclickreg.reg (the bold bit is the most important you can label it whatever you want before that, also again if like me you don't have you default programs install folder on C: then edit the bold bit below so that it is directed correctly)
Once saved simply double click the .reg file for it too make the changes to the registry
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Folder\shell\Open In New Window]
[HKEY_CLASSES_ROOT\Folder\shell\Open In New Window\command]
@="C:\\Program Files\\Internet Explorer\\IEXPLORE.EXE \"%1\""
Thats the ball rolling, now lets see what other little gems we can come up with.