Cels Forum

I currently store my cels in one of my fairly empty drawers in my file
cabinet.  I tie some fishing line from the ends of the metal hooks on 
the individual folders and hang the plastic cel bags on the line.
They're stored vertically and are sufficiently protected.  

I would only recommend putting cels in filing cabinets if your cabinet
doesn't have too much other stuff in it.  If the cels are getting squashed
with financial papers, the point of storing them vertically has just been
defeated.  

Another thing you could do is find a narrow box to put them in.

According to Bill Schacht(one of the folks at anime-cel.com) these cel books
can actually harm cels.  If there are too many in the book at any given time,
certain parts(paticularly those close to the spine of the cel book) will get
crushed.  It's even more harmful if you have a cel with a background.  

Reguardless of the storage medium you chose, keep a few of the following in mind:
*Make sure your cels are stored in a cool, dry and dark area.
*Don't bend or flex cels; keep over all handling to a minimum.
*Make sure your cel doesn't have any pressure exerted on it.
*If possible, try to remove the pencil sketches from cel and store them
separeately.  

Hope this helps!

Many thanks to Nick from Anime Chaos and Bill for their input.