Over the last few years I've read a lot of literary theory  and will frankly admit that most of it just doesn't  make a dent. It comes in, curls up in my brainpan like a very fat, very disa greeable cat  and goes to sleep, occasionally waking up to bat around my medulla oblongata  like a toy mouse.
Mainly, what I've come away with from all this reading are half-digested, sometimes gnomic , nearly always mis-remembered  nuggets of wisdom like "The author is merely an instance of writing," and "If a lion could talk, we could not understand him," and "Literature is the question minus the answer," and "Language is a skin: I rub language against the Other. It is as if I had fingers at the tip of my words."
What most, if not all, of the theoreticians listed below seem to do for me as a poet is to problematize language. They make it much harder to assume that meaning is an unchanging quality, so that the connotative properties  of any string of words becomes extremely fluid. They also provoke me to question that "I" person everybody seems so intent on writing about. (Let's face it, the pursuit of poetry is a sort of open invitation to one's more narcissistic  and solipsistic  tendencies. The reader being more or less a conjecture, the pleasure in writing poetry is not unlike dancing around in your skivvies  singing at the top of your lungs into a hairbrush  when no one is home). Even taking on the voice of a character one has made up or borrowed from history becomes layered with masks  and mediations . All of which greatly broadens the possible horizons  of any given poem, but also greatly complicates the process of creation. The trick, I think, is to make the acquaintance of these thinkers and their ideas, so that you can give them a friendly nod on your way somewhere, but not feel obligated to have long, dull conversations with them.
Some Leading Theorists:
M. M. (Mikhail Mikhailovich) Bakhtin  / Roland Barthes  / Jean Baudrillard  / Walter Benjamin  / Noam Chomsky  / Jacques Derrida  / Michel Foucault  / Rene Girard  / Julia Kristeva  / Jacques Lacan  / Edward Said  / Gayatri Spivak  / Ludwig Wittgenstein  /
If, like me, you get queasy at the thought of vast stretches of airless prose written by people you suspect are perpetrating an insanely byzantine  practical joke  on the world. I suggest the Introducing... series of graphic nonfiction. As the name implies, the books provide brief overviews of complex topics (The Theory of Relativity , Post-Modernism , Semiotics , for example), and intellectual biographies of seminal philosophers , scientists, and assorted Big Thinkers (see below). There is nothing dumbed down about these books; they are just straightforward, thumbnail explanations of key concepts on a given subject. Of course, because of the relative brevity of each volume and the complexity of the topics, the nuances of a concept may be lost, and in most cases, the graphics are fairly amateurish, but the books succeed, I think, in their main function which is to break up very dense ideas into manageably bite-size pieces. Introducing Derrida  / Introducing Wittgenstein  / Introducing Barthes  /
Odds and ends of theory and criticism from Harris County Public Library's collections:
American Poets of the 21st Century / Claudia Rankine & Lisa Sewell
The American Prose Poem: Poetic Form and the Boundaries of Form  / Michael Delville
American Writing Today  / edited by Richard Kostelanetz
Aristotle's Poetics  / Trans. Gerald Else
Clickable Texts: An Electronic Hypertext Linking Poetry, History and Culture : Issue 4 CP 2002. / [web site]
The Poetics of Disappointment: Wordsworth to Ashbery  / Linda Quinney [electronic resource]
If you have any theories (or theories of theories) of your own, please, send me a comment.
Photo Credit: Dekonstrukcja by eisenbahner 
Photo Credit: NO CONDOR! (from Introducing Wittgenstein) by pheezy (Evan P. Cordes )