Here are some more:
http://www.openforum.com/articles/17-best-tools-and-apps-for...
According to the FAQ:
> Pay the $20 pledge and follow the Zen Master’s instructions that are emailed to you
That said, I'm not very comfortable with this website since the parameters for success and the content of the program are not clearly defined before you commit... and 20$ isn't a throwaway amount in my local currency (besides there's the inconvenience that even if the money is returned, I will loose the currency conversion cost).
Basically, the Zen Master provides an assessment form for your evaluator to fill out and sign.
The evaluator you choose is the one who decides at the end of the 30 day VOW of NOW whether you have achieved zen mind through diligent meditation practice - and get a refund (or not).
This system provides feedback from a trusted peer, as well as provides a money incentive (your own money).
Plus, this one is for meditation only, and has feedback, I doubt any of those links would give specific advice on meditation like this site does.
For people interested in meditation, I believe this is actually a great app.
I could spend a little more time searching for a list of exclusively free habit forming tools (or prepare one) but that's not necessary to prove my point.
My point is that free alternatives exist.