yRead

yRead will load a plain text (TXT) or HTML file and display it in a single-column, resizable window. Then it will read the file to you out loud, using human speech. You can even get voices for other languages. Use it to listen to eBooks, your own writings or any other piece of text.

Here's another suggestion: Load a book into yRead, set up a sound recorder on your PC, then play the yRead file. The recorder will save to a WAV (which will be huge), and then you use a WAV to MP3 program like CDEX to condense the finished file. Once finished, transfer the MP3 file to a portable player and you'll have an audio book on the run.