Below is an oil painting depicting Boromir from The Fellowship of the Ring. Just look at all of those details in everyone's clothes, all the branches, all of the different faces!! Great, great work.
I love his painting of Éowyn (*ahem* I mean Durnhelm) and Merry. The sense of depth is fantastic, even though you cant see all of the men in the background, it still looks like there's a whole army of them there. The horse details are a nice touch as well.
The last painting I want to talk about is this one of Strider, I'm assuming he is in the Prancing Pony. I think it captures this quote quite well. "Suddenly Frodo noticed that a strange-looking weather-beaten man, sitting in the shadows near the wall, was also listening intently to the hobbit-talk. He had a tall tankard in front of him, and was smoking a long-stemmed pipe curiously carved. His legs were stretched out before him, showing high boots of supple leather that fitted him well, but had seen much wear and were now caked with mud. A travel-stained cloak of heavy dark-green cloth was drawn close about him, and in spite of the heat of the room he wore a hood that overshadowed his face; but the gleam of his eyes could be seen as he watched the hobbits."
Definitely go check out Matthew Stewart's artwork! Now. Do it now.