Here is a list of some of the high-end sources on modeling techniques. Some of these come from renowned masters, others are galleries of outstanding works.
So here it goes:
Personal blog of Mig Jimenez, one of the most distinguished members of modeling society. Mig was behind creation of MiG Productions and AK Interactive companies which proved to be an indispensable source of weathering resources. Mig is also the author of countless video and text tutorials on weathering and is the inventor of many well-known techniques.
Personal blog of Jamie Haggo, a master who creates amazingly realistic models and dioramas. He runs the Scale Aircraft Weathering Facebook page.
Blog of Gary Wickham, an Australian modeler who works out details to incredible level. He also runs the Scalespot-Models page on Facebook.
Blog of Diego Quijano from Tenerife, Spain. Calling his works astonishingly detailed and realistic would be a ridiculous understatement. He also posts on Facebook.
Blog of Manuel Gil, a modeler I’ve discovered only recently. Manuel possesses great mastery over realistic painting; he also does superdetailing. His works were featured in several modeling magazines and his build logs are neatly presented and very informative. He is also on Facebook.