Is there any official cover art for the following demos?
- Pipe-Smokin' Brick
- John Peel Sessions
- Barbie 7"

Only 1 of those is a demo (Pipe Smokin' Brick) and the artwork (both small and large/high quality -- scanned by myself) for the demo tapes are in the .zip files on this site where you download the tape.  The smaller artwork is also at my other website:
http://fireska.sitesled.com/ash.html

The Sessions 7" doesn't have artwork... it is just a black vinyl in a sleeve that came inside early copies of the Trailer 12" EP.

You can easily find the Barbie 7" artwork by looking around online and doing searches on Google.  Here's a small screenshot of it:
http://static.rateyourmusic.com/album_images/f6a486dbd3502b342afd5cf9e5e588a6/155707.jpg

Thanks FireSka.  Just a note, the artwork for Pipe-Smokin' is not in the zip file.