Use shortcodes for blog URLs, post URLs, and template URLs so that your posts always have the correct internal links.
Adds shortcodes [blogurl], [posturl], [templateurl], and [childtemplateurl] for WordPress 2.6 and up. Use [blogurl] to generate your site URL. It offers the parameters "slash" and "noslash" (to add a trailing slash; [templateurl] and [childtemplateurl] also support this), as well as "uploads" to produce the URL of the uploads folder and "wordpress" to produce the URL of your WP files. Use [posturl id=3] (replace "3" with a post ID) to generate the permalink for any post.
[blogurl] will generate
[blogurl wordpress] will generate the URL to the root of your WordPress files, if they are in a different location than your site root
[blogurl noslash] will generate
[blogurl uploads] will generate
[blogurl uploads noslash] will generate
[posturl id=375] will generate the correct permalink for the post with an ID of 375; for example, <a href="[posturl id=375]">post about this plugin</a> would generate post about this plugin
[templateurl] will generate the URL to your parent theme's root
[childtemplateurl] will generate the URL to your child theme's root