I'll start off with a few of my own:
Disable Resume on a per-app basis
You can disable resume on an per-app basis by locking the folder inside ~/Library/Saved Application State (~ = Home folder) that corresponds with it. You guys might find this useful if you're looking after disabling resume for - let's say - TextEdit only, rather than system-wide.
Make the ~/Library folder visible again
Launch Terminal located in /Applications/Utilities or via Spotlight, type in the below command and hit return.
chflags nohidden ~/LibraryAlternatively you can hide it again by typing in
chflags hidden ~/Library
Get Drag Lock back when using a trackpad
Apple moved the Drag Lock preference from the Trackpad preference pane to Universal Access. Go to System Preferences > Mouse & Trackpad > Trackpad Options...
Change the Dashboard space background pattern
What to do:
1. Replace pirelli.png in /System/Library/CoreServices/Dock.app/Contents/Resources with a desktop picture of choice. Be sure the image matches the exact resolution of your screen and has a dpi of 720.
2. Make a second version of the desktop picture only this time 256 x 144 pixels in size (might depend on your Mac though) and replace mini_pirelli.png also located in the same directory as above. That way the background in Mission Control also gets changed.
3. Restart Dock.app using Activity Monitor or Terminal and repair disk permissions afterwards with Disk Utility.
Remove Finder sidebar items
In Mac OS X Lion and Mac OS X Snow Leopard v10.6.7 you now have to hold down the command key on your keyboard in order to remove items from the Finder sidebar.
Hide apps from Launchpad
You can use this tool to hide apps from Launchpad.