The problem: In digital documents, "hidden" information may not be truly secure. In 2003 the U.S. Department of Justice released a PDF file of a workplace diversity report with heavy redactions - black blobs that covered sensitive portions of the text. The secrets didn't stay secret for long: The censored text was easily recovered by editing the file in Adobe Acrobat.

The solution: Wise use of your word processor settings can limit the release of compromising document metadata, while PDF redaction software such as Appligent's Redax can keep you from inadvertently publishing a tell-all. The National Security Agency (which knows all about hiding secrets) has created a detailed how-to on cleaning files. Search Google for "Redacting With Confidence."