Here are some of the top headlines that resulted in high click-through rates:
#1. Headlines with numbersNotice that most of these are either lists or stories that are controversial. You can apply this to your blog as well as Problogger recently demonstrated the successfulness of lists. In addition, one of the other reasons that Career Builder's newsletter became much more successful is becuase they moved away from using it as a sales tool and more of an informational piece. This is something that I had talked to earlier in my post "Linking Blogs and Newsletters Together".
"7 Tips for Improving Your Cashflow"
"Top 10 Interview No No's"
"Top 10 Recruitment Myths -- Busted"
"Top 10 Sales Killers"
"5 Traits of Great Leaders"
#2. Stories with a controversial angle
"Are Your Employees Telling the Truth?"
"Eliminate 10% of Your Staff Each Year"
"Get Your Underperforming Employee to Quit -- Counseling Out"
"Top 10 Excuses for Being Late"
Have fun blogging and remember that as good as your content may be, if the headline isn't good, no one will read it.
PS - Also check out the recent ClickZ article "Ten E-Mail Starters to Break Writer's Block".