I do this with other writers' work all the time (without their knowledge, usually). I have been scanning some old visual pieces to send to Christophe Casamassima, which got me thinking about appropriation as collaboration. I have used a lot of different texts in a collaborative way--works on fire suppression techniques, the Salem witch trials, the function and nature of the eye, and works by Freud, Cotton Mather, and Susan Brownmiller.
Christophe suggested the possibility of collaboration--a prospect that excites me--of course there is the question of what would that look like? I haven't completed a collaborative piece with another writer since Deborah Richards and I wrote the chapbook Cut and Shoot together in 2001. I enjoyed the work, the back and forth, the getting-out-of-my-own-mind that the collaborative space provided. I have been looking for ways to explore that space again. This is an example of how I've been comfortable with collaborating (from my maybe-chapbook "No Delicate Flower," which employs Susan Brownmiller's text Femininity),

but I'd like to work in new ways, with more than just my own parameters to contend with.
In my work-life, I wanted to create a collaborative blog where researchers could comment on the organizational structure and description I provided for the Chew Family Papers, but I never quite had the time to make it happen. In retrospect, however, I'd rather save that energy for collaborative poetry. I'd love to hear about others' projects, collaborative desires, or the logistics of collective work. Leave a comment, or just email me at deliciousginger at gmail dot com if you're interested in exploring this kind of work and/or conversation.