Probably one of the best fantasy city supplements ever developed, City of Lies gives a GM all the tools necessary to run ongoing, long-term campaigns in Legend of the Five Rings. The player's guide to Ryoko Owari is one of the best handouts I've ever seen for city plot development and NPC character information - it tells your players who these guys are, what each part of the city is about, and the major plotlines and unusual practices of the city. It hints at the plots that could be run without giving anything away. I owned the print version of this supplement but I bought the PDF version solely so I could print out several copies of this document for my players as a handout.
The rest of the supplement is equally high-quality. There are handouts that are of use to the players, plots, pre-written adventures, adventure hooks, random rumor generators, ideas about how to create random encounters using the personalities and places in the game, a big map, and so very much more, all written with the high-quality that one can expect from an AEG - Rokugan based product.
I love this supplement, and I was thrilled to find it available online. I highly recommend it.