[fred_durst]

Back button hijacking like this is spam. Please stop selling this product. When someone hits the back button they want to leave. Forcing them to stay on the site after that action is wrong. Shameful. I know you won't care, because people who create things like this don't have an ethical compass, but sometimes I just can't help myself.

[danieltillett]

I agree. There is one legitimate use of this type of product and that is at the end of sale funnel. I have found on one of my sites where the customer is shown the final confirmation page that they sometimes leave without submitting even though their intent is to complete. It seems that some (most) customer don’t (can’t) read and think that they don’t need to confirm their order is correct. If they click away or back out at this stage I ask them if they really want to do this as they have not yet submitted their order. I find I catch around 15% of customers at this point turn around and submit the order after getting this message so I can only assume that I have saved them from a mistake.

[avalaunch]

Another legitimate use is when you're in the middle of designing something (drawing app, for example) that you might have spent a long time on and hitting the back button will lose your progress.