• Don't get too clever with your subject lines.  Readers prefer clarity to creativity in subject lines, with creativity better utilized in the body of the post.
• In data analysis from AWeber, clear subject lines outperformed creative subject lines in the following categories: 1107% more comments, 315% more tweets, 331% more Facebook likes, 617% more traffic, and 366% more email subscriptions.
• Examples of clear subject lines: "Email Timing: A Look At 6 Marketers", "Email Marketers, Here’s What to Watch For in 2012", and "What Do Teens Really Think Of Email?"

From the article:

The original title of this post was going to be Turns Out This Particular Post Title Sucks. Turns out, that particular post title would have sucked.

See, as good marketers do, we recently sat down to analyze how well our approach has been doing – meaning, how well you guys like our posts.

The first thing we found was that you guys do like them – all your comments, tweets and the like made us feel pretty appreciated. So thanks for them, and we appreciate you back.