New iOS 6 Safari comes with Web Inspector feature which allows to connect to it from your desktop Safari via USB cable. It then allows you to debug pages opened in iOS Safar
I regularly use weinre
. It basically runs a webserver that in turn acts as an inspector-enhanced proxy to browse webpages and websites. The inspector can be started by adding a script to your page or running a bookmarklet.
weinre is a debugger for web pages, like FireBug (for FireFox) and Web Inspector (for WebKit-based browsers), except it's designed to work remotely, and in particular, to allow you debug web pages on a mobile device such as a phone.
To install it, you will need NodeJS and NPM (included with NodeJS). You will also need a WebKit-based browser on the desktop/receiver end (Safari, Google Chrome, or Chromium). It should work on Windows, OSX, and Linux.
If you already have NodeJS and NPM installed, you can install and run it with:
npm i -g weinre
weinre
# Go to the URL that it outputs for instructions to use it
@EvAlex has pointed out another tool very similar to Weinre called Vorlon.js. It is pluggable and supports viewing/switching between the inspector of multiple devices simultaneously.