How to get the value of a node field?
To get the real value and not  a themed one...

You can use http://api.drupal.org/api/drupal/modules!field!field.module/function/field_get_items/7 

 $my_field_items = field_get_items('node', $node, 'field_my_field');


Or use Entity API module and entity_metadata_wrapper 

 $node_wrapper = entity_metadata_wrapper('node', $node);
 $field_val = $node_wrapper-&gt;field_test-&gt;value();


Take a loot also at http://www.computerminds.co.uk/articles/rendering-drupal-7-fields-right-way