I also would benefit from this app. Add me to the Epic Wants list too. I sell artwork in my store, and often have to pack very lightweight objects with lots of packing, meaning weight is not a good qualifier for shipping cost. I also sell very small things at very high prices, or larger things at comparatively low prices, so price doesn't work well as a determinate either. It seems to me that being able to specify shipping rates for individual products, and being able to offer shipping options for those products is a good solution. More work for whoever is creating the product, but ultimately more flexible and accurate, which can save money!
Upgrade your shop to have access to the Carrier Shipping API so you can offer custom rates per product. With that you can assemble a shipping price that is deadly accurate per product. For example, you can ship a heavy small box from New Jersey for cost $X and a light huge box with Dim Weights from Dallas with price $Y on the same customer order where they see the price $X + $Y.
It frees you up from making crazy guesses about shipping costs when you control the shipping rates you present to your customers. I have made many custom Apps that do just this, to the satisfaction of the merchants. Due to the large amount of variance in what a merchant may actually need, it is hard to find a one-size-fits-all solution for this, hence the great option merchants have of drawing up exactly what they need.
Found this topic and I think this app might fit your needs: https://apps.shopify.com/checkout-boost
This app allows you to set free shipping for some products in store only, depending on your choice.
Moreover, you can also set free shipping, free gift or discount to customers if they share their cart on Facebook, Twitter,... It will not only encourage them to finish their cart to catch your offer, but it will also help you reach more new customers on social networks.
Hope it helps :)
Please add my name to this epic wants list, I offer free shipping over a certain cost - but am now starting to sell much cheaper products as well - those customers really don't want to pay shipping, so I need to be able to set it on a product type basis.