This mod was originally written by a_berezin and has never been released before(according to Voltage).
I'd like to thank a_berezin for coding this very useful mod, and Voltage who was so kind to send me the code.

I. Feature:
This mod will allow your customers to set the maximum number of products to be displayed per page.
Please note that this does not work in "All listing", "New listing", and "Special listing". The reason is that each of those listings actually has each own module (with all the querying, and stuff. I just can't understand why ZC can't try to use a single module and template for all the listings)
This does not mean that it's impossible, it's just that I don't have time for that now.

Link to download:
http://www.zen-cart.com/downloads.php?do=file&id=496