The Planescape Conspectus is basically just an ad that came with Dragon Magazine, and has no substantial new information. It's a bunch of images from Planescape products crudely Photoshopped together on a fold-out poster, with some explanations of what Sigil, the factions, and the Outer Planes are.
The Planescape Sketchbook was a book of conceptual art Dana Knutson made for the campaign setting available at Gen Con one year. There might conceivably be some drawings of Sigil NPCs in it that might be indexed, but that wouldn't be useful to many people.
The other sources you mention seem worth adding to the index. Off hand, I know there's at least one major Sigil NPC in the PSMCIII, and it'd be fun to add characters from the Torment novel (some of whom also appeared in Dragon #264). I don't have the Blood War trilogy or In the Abyss, but I can do the others.
I haven't been able to read the document, by the way - perhaps it's a problem with trying to read an .xls document with Microsoft Works? Regardless, it keeps making Microsoft Works crash.
![:]](http://www.enworld.org/forum/images/smilies/devious.png "Devious :]")
