I don't know if this service is mentioned on this forum much (a search only shows two posts from 11 months ago), but an article in today's Wall Street Journal described an app that auto deletes texts. This could be used by cheating spouses, and unfortunately it's free:

http://online.wsj.com/article/SB10001424052748703740104576122460926972084.html?KEYWORDS=tigertext

I would recommend snooping to make sure this app is not on a spouse's phone.

Off-topic. ImStaying, shoot me an email. I have some diet and exercise stuff I want to go over with you for this article series I'm working on for an online health blog.

Moderator's edit: removing email address