To start off both Watchmen Week and Sunday Spotlight, here's some art drawn by one of Britain's best artists and co-creator of the Watchmen series - Dave Gibbons. Originally, I remember Dave Gibbons from his art on Harlem Heroes and Robusters in Starlord and then 2000AD. Although I didn't much care for the Harlem Heroes (basketball players in rocket-packs?!) I thought the pictures were impressive and very detailed.
Of course, Dave has also produced other work, such as on Doctor Who (see above) and Green Lantern, but he's best known for his work on Watchmen. The first image above is taken from the cover of the Watchmen RPG (I think).
For more Dave Gibbons goodness, see his fansite or the Art Droids site. DC Comics also has a Watchmen minisite containing some of his sketches and art.