There are several web sites dealing with matte art, but the one I tend to follow is Matte Shot, hosted by a semi-anonymous New Zealand blogger and featuring matte work from pre-digital times.
A recent post features Mark Sullivan, who began his career making matte paintings in the waning days of that era and now does a good deal of digital work. His web site is here.
The Matte Shot post consists of a long interview with Sullivan and a collection of images, some of which I include below. The majority of the interview is in-group chat dealing with personalities, something of interest mostly to matte painting fans. But if you scroll down to some point in the second half, Sullivan discusses his approach to matte painting, something of interest to artists in general.
Some matte painters such as the great Albert Whitlock usually favored a freely painted, almost impressionistic style. Sullivan paints more tightly, especially in areas near where the live action will be composited. He assumes viewers will be focusing attention here, rather than on other parts of the screen where he loosens his style.
I find matte art fascinating because of its final effects that are divorced from the need to be accepted as Fine Art painting, yet remain impressive examples of craftsmanship carried out under severely constrained conditions.