One time when I did an assessment of my talents, interests, and abilities I came to the conclusion that the perfect job for me was "doodlist." Not cartoonist, because that sounded too formal.
So I was intrigued when I saw that someone had stumbled upon TTGSiMH by using the search terms "doodle test patterns personality." I thought 'Yes! What about doodling and personality?' So I went hunting. The BBC has some advice on Doodle Analysis, including symbolism. There is also Anna Koren's Graphology page for Doodles. And About.com has a page on Doodle Interpretation.
Personally I mostly doodle across the top and down the left hand side of the page. According to the links, that means that I am "an energetic, free-thinking, spiritual person" (top) but also affected by "the past, nostalgia or regret. It may indicate apprehensiveness for the future" (left). Fortunately they point out what I was thinking about the left side of the page, "separated by a margin, or with punched holes waiting to be decorated - is also prime doodling real estate." If you have any sense of space it is just the easier place to doodle.
My most common doodle when at work is of repeating geometric patterns, especially triangles. "Regular patterns from geometric shapes tend to indicate an organised and efficient mind. Triangles are a geometrically stable shape but also suggest direction and sense of purpose."
I also like to doodle vines and flowers. Anna Koren tells me that means I'm "friendly, sociable (motifs used extensively by social workers), sensitive, humane, warm, open."
I couldn't find any references to tell me what it means when I doodle Garfield and have him say something sarcastic about the meeting topic.