Are there particular monsters that drops certain loots or everything is really random?
Trion just added this new log to help zam track basically what you are asking for. Right now you can help in zone events and get the blue sourcestones and some planerite as rewards. It is going to take some time to get statistics and exact notes so Zam can build their database up.
There is something called a rare planar vendor who has Blue weapons in exchange for those currencies in Freemarch and Silverwood. Edited, Jun 23rd 2011 10:58am by Puremallace