We discovered that existing tools for looking at the PGP web of trust are not well-suited to answering the question "do I know the person who just e-mailed me, and do I trust this key?". Existing PGP clients only answer this question for keys that already exist in your keychain. Here, we have software (called "sigtrace") that will tell you how you trust a given keyid.
You can fetch the software by cloning the Git repository at
git://wot.scripts.mit.edu/firegpg.git or run it out of the "wot"
locker on Athena.
The latest data files are available here. We also have a dump of the signature set as ASCII text, if you want to use the data to produce your own software.