Howto accurately position images with maximum flexibility?

I wrote a plugin named »Dynamic Image resize« for exactly that purpose. It features a template tag and a shortcode (that takes the exact same amount of arguments, the template tag takes.

// The args need to be an array
dynamic_image_resize( array(
     // The full path to the image in your uploads folder
     'src'     => 'http://example.com/wp-content/uploads/2012/03/some_image.png'
     // OR: the ID
     'src'     => 6

    ,'width'   => 60
    ,'height'  => 100
    ,'classes' => 'some classes to align and style the image'
) );

You could even make it even easier and add a “child”-plugin that offers a TinyMCE button.