Smashing magazine have a nice list of Adobe Illustrator tutorials.
Over years Adobe Illustrator has become the standard application when it comes to illustration design. Artists, illustrators and graphic designers use Illustrator to create vector-based graphics which — contrary to raster-based editors such as Adobe Photoshop — can be easily rescaled without the loss of quality. E.g., Illustrator is often used to quickly transform hand-drawn sketches on a sheet of paper into lively and colorful digital images. However, to master Adobe Illustrator isn’t easy; and the creating process of professional illustrations requires both time and patience. Therefore tutorials can turn out to be real life- and time-savers as they show exactly what needs to be done in order to create professional illustrations and how masters of illustration actually manage to do their magic. Click here to view them on Smashing Magazine