Terminal:
Force Safari To Open New Windows In Tabs:
defaults write com.apple.Safari TargetedClicksCreateTabs -bool TRUE
Force Expanded Print Dialogue Boxes As Default:
defaults write -g PMPrintingExpandedStateForPrint -bool TRUE
Force Expanded Save Dialogue Boxes As Default:
defaults write -g NSNavPanelExpandedStateForSaveMode -bool TRUE
Safari:
For this last one, create a bookmark in Safari (I called it "Maximize Window") and copy in paste the code below into the "Location" field. This allows you to maximize any window (works with the current active Safari window) to full screen. Once the window is closed, the window size is forgotten. Great if you need full screen quickly while browsing but don't want a gigantic window when you reopen Safari.
Maximize Safari Window Bookmark:
javascript:self.moveTo(0,0);self.resizeTo(screen.availWidth,screen.availHeight);
Also, checkout
MacPilot as it is a great GUI for lots of OS X and application hacks. It also has a great toolset of utilities.