klieb2000's tip about importing CSV data into AppleWorks mentioned a workaround for typing a tab into a textarea (rather than tabbing to the next control). Instead of copy pasting a tab into the find and replace fields, just press Option-Tab (or Option-Return to type a carriage return) instead of activating the default button).
Using the Option key to switch the default behaviour of tab works in most applications with a find box (Safari, TextEdit, Terminal, etc), and even works in some applications with multiple text fields. For example, Option-Tab in Eudora allows you to tab from the body field to the subject field instead of typing a tab.
One disappointing exception is Mail. The only way to escape the body of the message from the keyboard is to Shift-Tab (incidentally, there is also a bug in Mail that stops you from tabbing between the fields in the find/replace dialogue box ... again you have to Shift-Tab).
Mac OS X Hints
http://hints.macworld.com/article.php?story=2003120120294256