I started this project a month back on Ruby on Rails.
First the project was a Public Kill List, like the users will be able to post the people they want to kill with reason and others can comment on that.
Now the site is a private todo list like a kill list.
You can check out the demo below:
http://mustkill.com
user : demo
pass : demo
there is no admin panel.
Currently there are 80+ users.
There is not much of revenue, I just implemented Adsense 2 days back.
This site has a lot of potential, if advertised properly.
I will provide installation support if required.
Payment mode : paypal
Starting bid: $200
BIN : $1000