Frequently when using the AutoNav plugin, the Hierarchical Pages Widget or other plugins which depend heavily on nested pages and on attachments to pages and posts, one finds that a page, or an attachment, needs to be moved. Here are two plugins to handle these tasks easily:
Pagemash lets you move pages up, down, in, out, and around your hierarchy with the mouse. Amazingly easy.
Change Attachment Parent is an easy way to reset the parent page or post for any attachment, right on the attachment's Edit screen in the Media Library. You do need to know the new parent's ID, though.