Safari 3 - close tab
10:30:52 MST on Wednesday August 29 2007 #For my future reference, and others. To get rid of the annoying "You have entered text on XXX. If you close the tab, your changes will be lost. Do you want to close the tab anyway?" dialog box just run:
/usr/bin/defaults write com.apple.Safari DebugConfirmTossingUnsubmittedFormText -boolean No