Is there an Android phone without proprietary code? I want to buy an Android phone. 

However, with everything that is happenning in the IT world today (all the backdoors, "Carrier IQ" stuff and so on), I am more and more convinced I want a trully open OS - that means, without proprietary applications, without proprietary drivers/"binary blobs" - or, at least, with at least of this as possible. (Stallman-style!)

I know that one fully open phone is OpenMoko phone, but that's not an Android and it has very outdated hardware. Is there another possibility?

(I see that this question on Android SE was marked as unconstrictive for some reason; I hope this won't be too)
Geeksphone started off with the premise of a completely open software and hardware stack.  So far they released two handsets, One and Zero.  Although both models are severely outdated specifications-wise compared to today's high-end models, the "Zero" model is quite comparable to current mid-range devices.

The company provides source code for the kernel and drivers of their "One" model on the web site.  I couldn't find the sources for the "Zero" model, but I'm sure they will if you reach out to them.