The question of copyrighting one's work is one of the very few issues in the world about which I still hold a "moderate" stance. One the one hand, an artist (be they cartoonist, musician, author) wants and should be compensated for their work. On the other hand, the goal of many artists is to spread their work to as broad an audience as possible.  As of now, my opinion changes on a case-by-case basis.
As a child, I was obsessed with the concept of copyrighting or somehow "protecting" my work—my drawings were a private thing, I did not ever want to see my cartoon characters conceived by the imaginations of my family and I reproduced in someone else's hand. To a seven-year-old with an anxiety disorder, seeing your original ideas bastardized by a classmate's sloppy hand triggered a sensation akin to gouging sporks into your eyes. My dad helped to calm me once by telling me that technically whatever I created, I owned, and no one could take that away from me. (As I got older I also realized that one could easily differentiate poor imitations from the real thing—I really shouldn't have worried about my ideas being stolen when the imitators just plain sucked.)
Nowadays, most likely in part because a great amount of my work is created for use in the public sphere, I am much more lax about who can distribute it and where it can be distributed. Perhaps because I am not spray-painting original characters onto walls or using them in promotional literature for academic conferences. My art has gotten more "universal," and in this way, more "accessible;" someone is more likely to enjoy/utilize a picture condemning Israeli Aparthied or drawings of recognizable world leaders than my original cartoon characters and their adventures. That I create things for an audience at this point in my life and work is not an inherently good or bad thing, simply a turn I have taken.
Following are three recent cases in which I judged the use of artwork and compensation on a case-by-case basis. A very nice guy from DeviantArt sent me a message asking if he could use my drawing of a guillotine on a t-shirt for school. (I had no idea where that was headed, but I cooperated because you don't fuck with Madame la Guillotine.) We came up with an agreement that he could use the image if it wasn't altered for the most part, and if my name and/or web address could be put somewhere on the shirt. I think we reached a good compromise: in the end he got to use my drawing for free, and I got free (on my part) exposure. (And a student group that uses a bloody guillotine for their club t-shirts... that's just fucking awesome.)
I ask for money from those who can afford it, or take how much one is willing to pay. I have started asking to be paid for my commissions by the local theater in my town whose posters I have been designing for years. I thought a small amount of money per drawing would be a fair compensation, since I work on deadline, follow graphic specifications, and am advertising for already-existing theater plays which, were the theater not using my logos, would charge the community theater for the right to utilize the copyrighted graphics of Music Theater International or other said company for the purposes of publicity. Someone asked me if I would continue designing logos even if I weren't compensated fairly. The answer is that I probably would, for the love of it, but the fact is that I need to eat. I need to buy art supplies. I need to pay off thousands upon thousands of dollars in student loans.
In terms of educational materials and the distribution of radical literature, I am of the opinion that we (of the revolutionary school of thought) should help each other out where it's possible. A friend of mine recently turned an entire book into a .pdf file and e-mailed it to every social justice group in which he is involved. I devoured this book, and agreed that it was useful and should be read by anyone identifying as progressive. Photocopying and distributing a copyrighted book is probably illegal. The author wrote the book, however, to deliver his message to an audience as wide as possible. This was accomplished through the photocopying and e-mailing to hundreds of young activists. (Another friend of ours added that he knew the author, and in his opinion, the author would be fine with our decision.)
What are your thoughts?