Most folks have a few documents--legal forms, business records, account spreadsheets, etc.--they'd like to protect from prying eyes. Here's a little-known fact: Word and Excel let you assign passwords to individual documents, and it's easier than you might think. Here's the procedure.

1. With the desired document open, click File, Save As.
2. Click the Tools button, then Security Options (or General Options if you're using Word 2007 or Excel).
3. Enter a password, keeping in mind that it will be required every time you want to open the document. Thus, make sure it's something you can remember! If you're concerned about forgetting, write the password down somewhere.
4. Click OK and you're done.

That's all there is to it. If you want to get fancy, you can click the Advanced button in Step 3 and choose from various kinds of password encryption--but that's probably overkill for most users.