En castellano:
- PHP
http://www.php.net/manual/es/

- HTML, JavaScript, CSS
http://geneura.ugr.es/cursos/tutoriales.shtml
http://www.ulpgc.es/otros/tutoriales/

- Linux, MySQL, PostgreSQL, Latex ...
http://es.tldp.org/htmls/manuales.html
http://www.programacion.com/bbdd/tutorial/mysql_basico/3/

- Manual Smarty
http://www.drclone.net/modules/freecontent/index.php?id=6

- Latex:
http://www.uv.es/~jgutierr/LatexAvanzado/LatexAvanzado.html

- HTML, java, PHP, ASP, bases de datos:
http://www.programacion.com/

- GIMP
http://gimp.hispalinux.es/modules/news/

En inglés:
- DHTML
http://gosu.pl/dhtml/mygosumenu.html
http://www.cross-browser.com

- HTML
http://www.htmldog.com/guides/htmlbeginner/

- PHP
http://www.php.net/

- Javascript
http://www.devarticles.com/art/1/272 (articulos)
http://www.w3schools.com/js/default.asp
http://www.docjs.com

- Javascript References
http://www.quirksmode.org/
http://techpatterns.com/web_design/frames_iframes/iframes.php

-Java
http://java.sun.com/webservices/docs/1.5/tutorial/doc/index.html
http://java.sun.com/docs/books/tutorial/jdbc
http://java.sun.com/docs/books/tutorial/security1.2
http://java.sun.com/docs/books/
http://javaalmanac.com
http://www.java2s.com/ExampleCode/CatalogExampleCode.htm
The Apache Jakarta project
Apache Struts
Tiles advanced (.pdf)

- CSS
http://www.thenoodleincident.com/
http://www.sitepoint.com/article/exploring-limits-css-layout/
http://www.w3schools.com/css/css_colornames.asp

- Regular Expressions
http://www.webreference.com/js/column5/rules.html

- SQL
http://www.sql.org/sql-database/sql-tutorial/
http://www.sqlzoo.net/

- Web Programming
http://www.brainjar.com/

( Se agradecen contribuciones, please ... :-D )