As I mentioned in an earlier post, I signed up and paid (~$11 USD) for a spot in the Fussy Librarian's eBook newsletter. On the day of the email blast I didn't see much of a difference, but the next day I sure did. It ran on January 24th and by the end of the day on the 25th, I sold the most books I ever have in a single day.
I suppose this could be due to the majority of people not opening their emails until the next day (coincidentally the 25th was a Monday, so maybe people were trying to kill time at work by sifting through their emails). Or, it could have just been a case of right time, right place - who knows. I'd really like to get the stats on how many people clicked the Buy link for my book in the email, but I don't believe the Fussy Librarian has a way of monitoring that.
My verdict? I will definitely be using them again!