The best way to do this is to use a inspector tool like Charles, HTTPFox, Fiddler, Browser Dev tools, etc. and filter on "utag." This will show you all the libraries that were loaded on the page. The number following "utag." will correspond to the UID number with TiQ. Ex. utag.13.js
This will only show what libraries loaded, not what data was sent. It is always good to check the individual requests that are made for each vendor to verify the data is getting sent correctly.
There really isn't anything available to accomplish this. If there were a simple code snippet that could be placed in an extension to output which tags loaded, it would give you the same information that Web Companion currently gives. It would show which libraries were told to load on the page and which tags were told to send the request, which WC already does. However, there is a difference between if a tag is told to send the request and the tag actually sending the request based on the conditions and configuration of the tag.
Some tags, like Channel Intelligence, may load on every page but only fire if specific query params are in the URL. So any script like this would show that the tag loaded and fired, but if the query params aren't present the request would never have been made. For this reason the suggestions above are still valid. Ghostery will show at a high level what vendors loaded on the page, but the network requests will show exactly what data is sent to each vendor.
Dan George brought up a good idea. You can enable Tealium logging using:
Run this in the console of the developer tools for your browser and Tealium will automatically log what tags were loaded on a given page. Maybe this is closer to what you were looking for?