Many programming editors have a very useful feature: They visually "match" pairs of corresponding brackets in some way and thus help to identify common syntactical and even logical errors. Without such a feature, the hunt for that damned unclosed bracket can be quite agonizing.
When writing logical formulas in MS Word, I have often missed a
similar feature, and once a certain "annoyance threshold" was exceeded, I
decided to write a VBA macro that provides this functionality in Word (well, kind of).
The basic idea is fairly simple and straightforward: While moving through the text, build a stack of unmatched brackets. When a matching bracket is encountered, remove the upmost opening bracket from the stack. Once the stack is empty, you're done.
Execute this macro when the cursor is next to a bracket. It will highlight (select) the text up to the corresponding bracket, including all nested pairs of brackets. When a mismatching pair (like "(foo]") is encountered, the macro will issue a warning. Thus, it is a syntax-checker and a selection helper at the same time.
Inspect the source code online and download the source or a Word document. If you prefer the latter, you should transfer the macro from brackets.doc to your default Word template (normal.dot) via the macro manager. If you plan to use it regularly, I'd recommend to assign a keyboard shortcut (e.g. Ctrl + M) to the macro.
Two cautionary remarks are in place here: (1) So far, I have only tested the macro in Word 2000. Be prepared for lots of more or less cryptic error messages in other versions. (2) Always save your work before executing the macro! Though I've taken some care to avoid the typical programming pitfalls, there is no guarantee that it is bug-free.