I have an interesting request:
I'd like to know if there is an extension or a way upon checkout for a user to see a message pop up if the system sees that for the price of shipping the user is paying that they can buy more product and pay the same for shipping. Does that make sense? Basically the extension will look at the weight of their cart and compare it to the shipping cost of a weight range and say "for the price you are paying for shipping, you can buy (so many more) pounds and pay the same in shipping!"
Anything like that exists?