Sometimes I want to copy/paste SQL from the source code to a command-line interface like mysql or sqlplus.  Tab characters are interpreted as tab keypresses, triggering auto-completion.  To get around it I have to open a blank file in a text editor, paste the SQL, convert the tabs to spaces, then highlight/copy it again.  It's a pain in the ass.  I can't be the only one with this problem, but I never see it mentioned in tabs/spaces debates.