My colleague Martha alerted me to the presence of pediaphon, a site which will create an mp3 of a wikipedia entry. The voice is a little annoying, but it could be a useful way to get your hands on some listening material if you are away from the ATC or Assistive Technology Room in the Library.
Another very useful site is Scribd. On this site, you can upload virtually any text and have it converted to a range of different formats for download, storage or sharing. So, you could upload your say in Word format and have it converted to pdf. Or you could upload a PowerPoint presentation and convert it to mp3 for listening in the site or for download.