JRequest is now depreciated and should be replaced with JInput library.

http://docs.joomla.org/Retrieving_request_data_using_JInput

JFactory::getApplication()->input->get('varName', 'defaultValue', 'filterType');
JFactory::getApplication()->input->set('varName', 'value');

 * @method      integer  getInt()       getInt($name, $default = null)    Get a signed integer.
 * @method      integer  getUint()      getUint($name, $default = null)   Get an unsigned integer.
 * @method      float    getFloat()     getFloat($name, $default = null)  Get a floating-point number.
 * @method      boolean  getBool()      getBool($name, $default = null)   Get a boolean.
 * @method      string   getWord()      getWord($name, $default = null)
 * @method      string   getAlnum()     getAlnum($name, $default = null)
 * @method      string   getCmd()       getCmd($name, $default = null)
 * @method      string   getBase64()    getBase64($name, $default = null)
 * @method      string   getString()    getString($name, $default = null)
 * @method      string   getHtml()      getHtml($name, $default = null)
 * @method      string   getPath()      getPath($name, $default = null)
 * @method      string   getUsername()  getUsername($name, $default = null)