How could I not put the creator of Twitter's failwhale on my list? Lu has a gorgeously simple style, usually with 3 colors or less, and minimalist shapes that have geometric/ traditional Chinese influence. She has done work on corporate logos, wine labels, and pet supplies among others, but I think her animal illustrations stand out as a canon of elegance.
Wachenje is an illustrator and designer who has done work for Levi's and Timberland, as well as portraits of hip-hop and pop artists among many other things. He defines the culture with a style that incorporates graffiti roots, urban attitude, and tough imagery. He does clothes really well, with nice folds and use of transparencies that add a good deal of layered effect.
Bannecker's illustrations are full of quaint characters, vintage color schemes, and layers of textures that really create depth and worn in feelings. A very impressive amount of work on his flash driven site, including book covers, Vodafone ads, and I swear he's the guy that graced the Modest Mouse cd covers of both "Good News for People Who Love Bad News" and "We Were Dead Before the Ship Even Sank." But that is total guesswork until I can check the liner notes.
Scott is a London based illustrator who crosses the line between still life and animation. His still images are superb, with an amazing amount of depth, color gradients, and pattern usage, enough so that I question what program he achieves this all with. His quality also carries over into his video work, which is comprised of music videos from Silverchair to Led Zeppelin to Salmonella Dub, a New Zealand reggae band, and commercials for Nokia, VH1, and Volvo.
Joe Whyte is another Illustrator from Australia, his work features a handful of editorials for magazines, as well as concert posters for acts such as Pearl Jam, Rolling Stones, AFI, and the Darkness among others. I like how he illustrates people, realistic, but toned down, striking content, very solid work all around. 
He illustrates for Oakleys, but has other personal pieces on his Flickr site. Marcelo's paths just exude style. I won't gush, but his layering of skin tones in the '07 ads are fantastic, his hair never fails to amaze, and the '08 stamp ads are truly phenomenal.
Lp is a Brazilian artist, heavily influenced by Picaso, abstract movements, and the flair of tropical aviary. Excellent line work, with his subject contents coming in and out of vision by becoming linear paths, splotches and color swatches. Vibrant and bright, his work screams South American culture, jazz, sensualism and whimsy.
