I think in many ways, agnostic can be a label that fits. What most people don't realize is that an agnostic can tend toward theism or an atheism... because all that "agnostic" means is that you don't know. The people we think of as "seekers" can often also be called agnostic. So long as you are on a path of learning, and understand that you don't know it all, I think you can fit in the broad category of agnostic -- and it can be liberating to realize it. All the philosophies don't have to fit cohesively, they just have to fit your experience.
To borrow from Steve's software analogy, you just load whatever software helps with the situation you're in. If the Tao seems to help you gain understanding in one area, then go with the Tao. If it's IM, go with IM. For that matter, even Buddhism, Christianity, Hinduism, Islam, Judaism, etc. can be software that help you gain understanding.
Then again, much of that is really only relevant if you're looking for a label. Personally, I try to avoid labelling myself like the plague.
And on an unrelated note, loved seeing Elaine Pagels on your list. She's written some great stuff -- and if you like what she's had to say, may I also recommend Bart Ehrman. His "Misquoting Jesus" is a good one.