If you were to show one cel to represent

Well, maybe if they have no idea about what a cel is.. hmm..hmm... I might show a sketch first to get her/his interest up.. =)
Then I'd get them really hooked later, like any good collector (dealer?) would ;P

This surely might be enticing:

http://e.rubberslug.com/gallery/inv_info.asp?ItemID=16044

Mmm ... tricky ... but I'd probably go with a cel that is intrinsically beautiful and dramatic, which doesn't require knowledge of the series to appreciate. Which means, in this case, one of my new ones:

http://sensei.rubberslug.com/gallery/img_b.aspx?ImageID=185850&Pass=

The Japanese know how to do hair!

Easy! I'd show this:

http://sc.rubberslug.com/gallery/inv_info.asp?ItemID=7450

It's from a popular series, has a back- and foreground, rough, layout, douga, genga, all forms of sketches, various layers, and is A1 End and B1 End and is oversized. I think it embodies all the various aspects a cel can have... or something like that. Hard to say.

^^
Anna

for me it would probably be this one;
http://majinvegetasrage.rubberslug.com/gallery/inv_info.asp?ItemID=64692

it doesnt need words ;)

I'am really impressed with the diversity of everyones choices. I think only two people chose cels from the same series and then from differnt parts.