you can set it to block/allow either categories, or individual sites. I found it to be the best filter for nofap
If you are using an iphone, turn on adult content filtering for websites in your settings. I just set mine up and am going to post my pass code right here, 5782, so I will have to go here when I forget and am trying to relapse!
Netnanny or mypornblocker. You can find download links under the 'useful software' section on http://theporndude.com/