A store I built has had issues with shipping cost calculations for some time. The shipping costs are complex: some items are always charged shipping (as supplied directly), one product has a shipping surcharge, depending on location, and all other products are charged a flat rate unless over a certain amount. No shipping plugin could handle this and we spend weeks trying to get this working.

Then I found this plugin. 10 minutes later, all the problems are solved using the Checkout Fees function. Superb! I'm sure the store will get much more from this plugin than just a fix for the shipping cost issues.