Internet download manager

 http://blog.joomlatools.org/2008/05/easier-debugging-in-joomla.html

http://extensions.joomla.org/component/option,com_mtree/task,viewlink/link_id,1509/Itemid,35/ 

Features
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This utility makes life easy for developers and template designers. You use it to see what's inside a variable, an array or an object. Instead of using print_r() or var_dump(), you can now use dump(). This will open a popup window with a nice expandable DHTML tree, showing the contents of the variable. It will even show a list of available methods for each object. You can use dump() in your extensions, in the core, in libraries and even in templates.

Using Dump
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Anywhere in your code, type:

dump( $variable, 'Variable Name' );

Simple huh? 'Variable Name' is optional and can be anything you like. If you use a lot of dumps, you'll want to use some descriptive names.

Shortcuts
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- dumpSysinfo();
  Displays a whole bunch of system information.
- dumpTemplateParams( $this );
  Use inside a template's index.php to dump the parameters.
- dumpMessage( 'Your message' );
  Displays a custom message. Very handy to check if a function or a loop is executed etc...
- dumpBacktrace();
  Displays the backtrace.