This site is full of information that I found on different places. The main thing I did was finding and ordering it in the way I liked. And the search still goes on.
Here is a list of resources I have used or which might be worthwhile to check out.
I suppose to not have violated any copyright. If someone is of the opinion that I violated his/her copyright, it can be notified to sybev@knoware.nl. Let it be clear that this is a non-commercial site.

Sources of audio/visual stuff on this site

The picture of the quetzal (quetzal.jpg) on the introduction page is from H. Miller's site.
The sound of the quetzal (quetzal.wav), is converted from Quetzal.au. Some information about this sound-file can be found at BirdSounds/Quetzal.txt

Sources of programming (Java / Javascript)

• The "Green Lightning" Javascript is an adapted version of the Fade Script ( Fade Script v0.1 by Kouichirou@Eto.com 1996). Website http://eto.com/JavaScript/
• The NavigationButton Java-applet was written by myself. For more information see my employer's website: Kender-Thijssen Business Communications, or go directly to the applets page.

Links

Sites with picture(s) of the quetzal
an amazon adventure--animals--quetzal, this site contains also quite some information about the quetzal
http://www.travellog.com/guatemala/quetzal.html
Defensores de la Naturaleza, site of a nature protection organization
Quetzal, in german, part of Das Überseemuseum
http://www.arconet.es/users/marta/quetzal.htm, in spanish, a picture and a few words
Resplendent Quetzal, observed near the Rio Savegre, picture
QuetzalCam, a webcam showing a Quetzal nesting, a beautiful archive plus more information

Maya-related sites: MayaQuest Related Internet Resources, a list with many Maya-related links
The Return of the Quetzalcoatl
Arte Maya Tz'utuhil Museum and Gallery, modern Maya art

travel links Resplendant Quetzal (etc, it's got a very long title), showing among others the best time of the year to see the quetzal (in Costa Rica).

Books

In the Land of Green Lightning, The World of the Maya, Thor Janson, 1994. Pomegranate Artbooks, San Fransisco, USA.