This morning, my wife and I woke up to find that the Android 2.1 stock browser simply stopped working. I timed a page load for Google and it was nearly 60 seconds when it finally came through. I searched for hours to find the solution, and finally did just now.

At some point, something entered in values for the proxy and port settings in the APN.
Go to Home-> Settings-> Wireless and Networks-> Mobile Networks-> Access Point Names-> [Your WAP].
We had to clear the proxy and port fields, and presto! The stock droid browser works again on 3G. Wtf?

This is on the Cincinnati Bell network.
Proxy value was: 216.68.79.202 and port was 80.

I should also note that Opera mini worked, even when the Android 2.1 stock browser gave up.