This article on 4GuysFromRolla.com demonstrates how to use ASP.NET and Web Services to snarf shipping quotes from UPS's Web site.
Author: Dan Anderson Code: ASP.NET Beta 1 & VB
It's easy to accept payments and respond to successful transactions using PayPal's IPN system. Use this code to get started verifying payments to your ASP.Net application and respond once the transaction is complete. Author: Patrick Santry Code: ASP.NET v2.0 & VB
For all of you ASP.NET developers out there who have yet to integrate a site with PayPal, just wait until you finally get to add that button to your form to pass the transaction details over to PayPal...