Following is the compiled list of useful resources for java and XML certifications. You may also suggest free resources such as articles, notes which you found useful. If you have your own articles/notes you wish to contribute,you can do so by sending them to moderators.

• Java Resources
  
  • Witscale's SCJP Resources
    • SCJP General information.
    • SCJP study notes.
    • The SCJP Handbook (eBook on SCJP)
  • Java Tutorial By Sun Microsystems
  • Thinking in Java by Bruce Eckel
  • Java language Specifications

• XML Resources
  
  • Witscale's Test 141 Resources
    • Test 141 (IBM's XML certification) General information.
  • The World Wide Web Consortium (W3C) website with interoperable technologies (specifications, guidelines, software, and tools)
  • Tutorials on XML schema, XSLT and XPath