This is a Firefox addon which records all the root CAs your browser trusts along with the associated hostname while you're browsing the internet. The idea is to build up a list of CAs which you actually use, so you can remove the rest (to reduce the level of trust you place in unknown entities).
The data is just dumped in a hard-coded JSON file, so you'll need to edit the code a bit to change that to suit your needs.
The addon can be built and run using the addon SDK. You can just use cfx xpi to package, and cfx run to run in a clean browser profile.