I took all my freebies off Kobo. Part of the reason why was that Amazon stopped price matching Sweet Tarts. The other reason was I couldn't tell if it was working. The Missed Wish was in the top 100 free YAs sometimes in the top 5. But it's a clunky list and I couldn't find Bad Apple on there. I had Flash for free for a week. It was just a completely unsatisfying experience. If Kobo can't tell you how many books are being downloaded, I don't want to play the game.
What I did instead was create a "new" book. 5 chapters of Flash as a sample and I put that for free at Kobo. Shortened the blurb by about 2/3. Next week I'll go back and make sure all my prices are back where they should be because going temporarily to 99 cents didn't produce 1 sale. I'll probably try this with a couple other books, too, but it's been very busy around here.
If a paranormal book is released you can pretty much expect it to be at the top of the chart momentarily.