On an older Ask TUAW we were asked how to add the Trash to the Finder sidebar. I pointed to several different solutions to this, but just recently reader DG left a comment on that post with far and away the most elegant solution. Basically, show the Trash folder in the Finder by clicking on the Trash can in the Dock. Next hit ???-i to reveal the "Trash Info" window (right). Click on the triangle to reveal the Preview if it's not already visible and then drag the preview icon onto the Finder sidebar and drop it.
This will place the Trash in the sidebar with the proper icon and you can now drag and drop files to the Trash from the Finder. Not only that, the icon will even animate to show whether the trash is empty or not (though it may take a few moments to refresh your Finder window so you can see it).