Adds support for percentage based shipping
Supports Minimum shipping amount (only added if order has shippable products and total shipping is less than minum shipping amount)
Default shipping can be a percent of total order
Products can over-ride default rate
This module is basically just a modified version of uc_flatrate.
I have not posted this module to CVS yet.
Please send feedback
I will post it to drupal CVS as soon as it is ready.