Real time shipping quotes are great, work great. For many shippers, the freight rates they want to charge the buyer are not always the same as the rates returned by the carrier's rate server. High volume shippers get big discounts, they often pass these along to their clients. Some shippers need to add markups or handling charges.
 
In the "Edit Shipping Type" page, it would be nice to have the following options for each shipping type:
 
1) Add a handling charge in % or $
2) Set a %markup to the realtime quote in % or $. Must work + and -
3) Set a maximum shipping cost
4) Set a "Flat Rate Threshold" where orders that exceed this amount are shipped for a flat rate. The rate should be settable.
 
This may not be necessary for small stores. Shippers sending >20 packages/day are running 10 to 65% off published rates with UPS and FedEx -- I'm sure they will need at least a basic markup function.

This is a very good list. I could use all of these. ESPECIALLY #1 which should be pretty easy to add.
 
In addition to the ones above:
 
5) minimum order amount in order to checkout (unless this exists and I just overlooked it)
 
6) shipping methods can require minimum order amounts in order to select... (e.g. USPS for all, but UPS if you spend $xx or more)
 
7) shipping methods limited to certain user types

We also would like this, as we automatically insure all orders over $100 with third party insurance. Right now we're absorbing this cost, but would like to add it onto the real time quotes for UPS and USPS.