Logo and theme images not showing after permalink change

Say your theme has a logo image. I normally keep non-css theme images in the images folder in the root directory. The logo is added to header.php with the path images/logo.jpg

If you modify permalinks, the logo will not show on pages other than the home page, because permalinks add a directory structure to your url, which break the img url.

The hack:
Where you have coded in your logo to your theme, use:
<img src="<?php echo get_option('siteurl'); ?>/images/logo.jpg" />