I came across the work of Mark Taro Holmes when I was struck by these two watercolor sketches on the Urban Sketchers blog. They were from his participation in the recent Sketchcrawl in San Francisco (see my posts on a previous Sketchcrawl, and here).
I then looked him up and found his sketch blog, SKETCHtaro, which has a wonderful array of his sketches, largely in watercolor or pen and ink, of both landscapes and figures.
His figure drawings have an engaging looseness, within the framework of accomplished draftsmanship. He has an unusual approach, sometimes drawing the figure in line, but multi-colored watercolor line, applied in brushstrokes that vary in weight and translucency as well as color .
His black ink drawings are frequently concerned with shadow and the play of light across architectural details.
Holmes is professionally a gaming concept artist and art director. According to his short bio on ConceptArt.org, he is currently the Studio Art Director at Ensemble Studios, and and has worked on gaming titles like Neverwinter Nights and The Lord of the Rings Online. MobyGames lists some of his other credits here. [Correction: Holmes has moved on from Ensemble and is now doing concept art for the film industry. See this post's comments.]