Above are illustrations by the famous Kris Atomic -- she uses an Intuos for her design work and did a great post on her whole illustration process a few months ago (link). She has such a distinct style. I love.
These two were done by my friend Gizem Vural. She's an illustrator and graphic design student in Istanbul, and she is frickin' amazing! Seriously. All the quirky and precise details, the patterns that are so prevalent in all her work, the narratives that each piece tells... I'm sort of obsessed. You can keep up with Gizem via Tumblr (link).
Maria Diamantes is an illustrator from Barcelona. I really love the imperfections in her lines -- they sort of run into each other at times, they're kinda squiggly, they're not totally consistent, but they are still very detailed and clean. Her drawings all have a very quaint feel to them. It's always nice to see personality in an artist or designer's work.
These illustrations were done by Rita, a graphic design student in Colombia. Gorgeous line work, really lovely textures. The last one is my absolute fav.