thanks for your suggestion (and all other suggestions)
Multi sellers, add add feature that show nearby sellers by ip addresses. This will allows buyers to buy locally and avoid shipping change . We can not beat two days shipping with amazon prime but this feature will be a big push when it come to shipping charge.
This might be a good idea for store with multiple sellers with chained stores or using the same shipping carrier, but not for all scenarios.
I think this will not be a majority.
using agile seller shipping module to allow sellers to create private shipping carriers and set different shipping fee based on his/her own location.
buyer is able to choose shipping carrier at product level.
using agile shipping estimation module, buyer is able to check the shipping at product page before add to shopping cart.