is there a list anywhere of all the cards that lower threat? if not can someone make one?
lowering threat
The big two are Galadrim's Greeting and Elrond's Council. Other cards in roughly descending order of usefulness are:
Gandalf (Core)
Aragorn (Lore)
Nori
Smoke Rings
Needful to Know
Ever My Heart Rises
Fall of Gil-Galad
Dwalin
Damrod
Free to Choose (cancels threat gain)
Elfhelm (cancels threat gain)
Song of Earendil (transfers threat)
Renewed Friendship (never seen it used)
Wandering Took (never seen it used, transfers threat)
and shortly to be at some stage in the future to be released Galadriel 
if you use the deckbuilder from zorbec, you have a filter based on mechanism that can show you all cards that are threat related.
Hall of Beorn Card Search now includes categories, so you can also find all threat-reducing cards here:
http://hallofbeorn.com/Cards/Search?Category=Threat+Control
Hall of Beorn Card Search now includes categories, so you can also find all threat-reducing cards here:
Wow, really amazing! Congrats
Blue Mountain Trader should be in there for resource smoothing. Herald of Anorien should be under ally mustering.
Still pretty awesome though.
Yes, the categories are automatically assigned using text analysis, so I need to continue to refine the patterns that I use for each category. Thanks for the feedback, I will include these changes in the next release.
I was wondering how you did it. Automatic text analysis is cool, but can be difficult to set up right to catch everything and not get false positives. O Lorien, for example, could be considered for both Ally Mustering and Resource Smoothing but achieves these effects by cost reduction. Vilya could be considered Ally Mustering, but it isn't limited to allies.
As time-consuming as it'll be, I'd prefer to do it manually (and that's coming from a programming who likes to make code do things for him) 
.
As much as I wish that I had the time to manually assign categories, there is only so much blood that can be squeezed out of a rock.
The good thing is that I am using multiple patterns for each category, and I have the ability to define exceptions, so I should be able to account for these outliers fairly easily. The real advantage to this approach is that new player cards are automatically categorized as I add them, which avoids a further delay from a pack's release and when it gets added to the search engine. If people in the community want to send me a list of any cards with missing categories, I will certainly appreciate the help.