Jace Wallace is a concept artist currently employed by Electronic Arts. Some of his more recent works include The Sims 3. But don't let that put you off what you're about to see.
Because what you're about to see is some beautiful art.
You can see a lot more stuff at Jace's personal site.
To see the larger pics in all their glory (or so you can save them as wallpaper), right-click on them below and select "open in new tab".