Root NOT needed
Proxy that can operate with proxy authentications.
Android OS has just proxy with no authentication.
So this app can help you with your corporate/university network environment.

Supports digest, windows (ntlm), basic authentication.
Drony will start if wifi appears that has proxy set on same port that is used in Drony to listen.
Drony will stop when that wifi is no longer active.

If you need more options, features check SandroProxy.
https://market.android.com/details?id=org.sandroproxy

How to connect to another proxy example:
http://code.google.com/p/sandrop/wiki/HowToConnectToOtherProxy