Tracey Rich writes  for the National Law Journal about using a company’s website against them.  Check out: Find Evidence on Your Opponent’s Web Site.  Rich reports:

"Browsing a party’s Web site will only show the information that the Web site owner currently wants visitors to see. Sometimes, the most valuable information about an opposing party is the information that has been changed or removed. Fortunately, there are ways to see older versions of Web pages. Pages that were changed recently can be viewed through Google’s cache feature. Pages that were changed months or years ago may be available through the Internet Archive, also known as the Wayback Machine. Viewing these older versions of Web pages avoids the privacy risks discussed above: The copied pages are not on the company’s Web site, so the company has no record of the researcher’s activities. "

Read about software that provides "enhanced cookie management."  Its one thing to find the information – but will your opponent know that you know?

Thank you to Disciplinary Board of the Supreme Court of Pennsylvania July 2008 Attorney E-Newsletter for pointing out this useful article. 

Addendum:  If you are interested in digital evidence, check out this ALI-ABA course:  Digital Evidence: Generation, Admissibility and Weight Considerations