In a comment Carriantor has pointed me to a tutorial (which has disappeared in the meantime, please try the tutorial from José Pablo Barrantes) about integrating phpDocumentor, a tool to generate API docs, into Eclipse. Thanks Carriantor!
Another short tutorial (there is also a German version available) about this topic has been written by Simon Speich.
Update 2008-06-21: Changed the link for the tutorial as the tutorial no longer exists at the original url.
Update 2008-07-28: Adding link to Simon Speich’s tutorial.
Update 2010-04-29: Fixing/removing broken links
Update 2010-05-10: Adding link to the English version of Simon Speich’s tutorial
Well thats nice but too bad that the tutorial lin goes to a 404 not found page.
@Webconsult: Thanks for the hint, I changed the link so that it points now to archive.org where the tutorial is still available.
If you would like you can link to this tutorial instead of the archived one http://www.speich.net/computer/artikel/integration-phpdocumentor-eclipse-en.php
@Simon: Thanks for the link! I added it to the article.
first tutorial : not in archive
second one : Error 404
…
@TangiX: Thanks for the hint, I fixed those broken links.
Sorry for the 404. The English Version is back up again. You find the tutorial here: http://www.speich.net/articles/?p=185
@Simon: Thanks for the hint, I added the link to the article.