Root NOT needed.
Capture, intercept, analyze, modify, replay http requests, websockets.
Can connect to another proxy (Basic, Digest, NTLM auth support)
Proxy can also acts as SSL man-in-the-middle.
It generates sites certificates on the fly.
Issuer is named UNTRUSTED.
Based on WebScarab.
For transparent proxy, superuser/su/iptables are needed.
There is gui for application redirection to transparent proxy.
Can act as Web server to access captured data.
Using Chrome Developer Tools remote web gui for display data.

If you would like some new feature in it, send request to
supp.sandrob@gmail.com
http://code.google.com/p/sandrop/

Example of usage:
Use stock browser and change that wi-fi uses proxy on localhost:8008
Check log tab for proxy activity, data tab for request/response content

http://code.google.com/p/sandrob/issues/detail?id=41#c27

★★★
there are ads on log tab and Google Analytics events on switching tabs
sorry for that
If you feel uncomfortable about this,
send mail and version without this will be build for you.
★★★

Screenshots: