for example, I have a shopping cart script which I am trying to find a specific div in, but instead of downloading all the files and doing a search, are there any other tools, e.g something similar to FireBug?
just use firebug or google chromes element inspector, right click something on choose "inspect element" at the bottom of the context menu. failing that you could always view the source and do a ctrl + F and type in what you want to search for.