Overide Number of Products per page for different categories.

I know where to set the number of products per page in the Admin>Maximum Values.

How do I setup, say 5 products on the page for category 1 and say 8 products for category 2?

What I am trying to achieve is:
In one of my categories I would like to have no products listed but when landing on the page have an image with clickable areas which would then take the customer to the product associated with that area.

Sounds like you're talking about 2 completely different things.

1. Different number-of-items-per-page per category.
   That's not a built-in feature. You could write custom code to do that.

But I don't see how that provides you anything related to your 2nd topic:

2. Category needs a navigation image map.
   In this case, put the HTML for the image-map into the category description.

I am asking how to do your number (1)

I am not asking how to do your number (2).
I still need to create the image, map it and put the HTML code in the product description but there is no point if I can't get the one category to show "zero" products

There's still something important missing from this discussion:

If the code is altered so that the category is treated as having 0 products, then how exactly do you intend to have its actual products get displayed?

ie: what category are your actual products really in?
If they're in the same category, how do you intend to make your "map" cause the actual products to appear?

Firstly let me answer your questions:

The category still has products, its just the landing page of one particular category that I would like no products displayed - just the mapped image. I would then embed each products URL into different areas of the image to get to each product.

The actual products are in the category.

The image will have the various URL's "mapped"

Maybe I misunderstand Zencart. Are you saying that if I enter a value of "0" in the "Configuration>Maximum values>Products Listing-Number per page" I will never be able to get to the products in that category not even by entering their URL in my browser?

My understanding is that I will not be able to see them on the Category page, but they will still exist and if I enter their exact URL I will be able to get to them.
If my understanding is incorrect - my idea will not work.

I hope that I have made sense here Dr Byte.

Is this for just one category, or will you want to do this with several different categories?

The following won't account for any filters by manufacturer etc. Just straight browsing to a certain cPath.

1. /includes/modules/pages/index/main_template_vars.php
   around line 195 you'll see code that looks like the following. Add the line in red, substituting '21,55' with a list of categories to treat this way
   (ie: 21 would work for cPath=21 and also for 75_31_2_21 since 21 is the current category regardless of parents):

  ////////////////////////////////////////////////////////////////////////////////////////////////////////////
  $tpl_page_body = 'tpl_index_product_list.php';
  if (in_array($current_category_id, array(21,55))) $tpl_page_body = 'tpl_index_product_list_hideproducts.php';
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////
} else {

2. Then create the tpl_index_product_list_hideproducts.php file in your includes/templates/your_template/templates folder. It's basically an abbreviated clone of tpl_index_product_list.php:

<div class="centerColumn" id="indexProductList">

<h1 id="productListHeading"><?php echo $breadcrumb->last(); ?></h1>

<?php
if (PRODUCT_LIST_CATEGORIES_IMAGE_STATUS == 'true') {
// categories_image
  if ($categories_image = zen_get_categories_image($current_category_id)) {
?>
<div id="categoryImgListing" class="categoryImg"><?php echo zen_image(DIR_WS_IMAGES . $categories_image, '', CATEGORY_ICON_IMAGE_WIDTH, CATEGORY_ICON_IMAGE_HEIGHT); ?></div>
<?php
  }
} // categories_image
?>


<?php
// categories_description
    if ($current_categories_description != '') {
?>
<div id="indexProductListCatDescription" class="content"><?php echo $current_categories_description;  ?></div>
<?php } // categories_description ?>


<!-- you could put custom HTML here (affects all special categories) if you don't put it into the category description (for individual categories) -->

</div>

Works perfectly DrByte - Thanks you very much

For anyone else that wants this, I had to add one line so it read:
Otherwise the image showed up between the Category name and the Product category image

<div class="centerColumn" id="indexProductList">

<h1 id="productListHeading"><?php echo $breadcrumb->last(); ?></h1>

<?php
if (PRODUCT_LIST_CATEGORIES_IMAGE_STATUS == 'true') {
// categories_image
  if ($categories_image = zen_get_categories_image($current_category_id)) {
?>
<div id="categoryImgListing" class="categoryImg"><?php echo zen_image(DIR_WS_IMAGES . $categories_image, '', CATEGORY_ICON_IMAGE_WIDTH, CATEGORY_ICON_IMAGE_HEIGHT); ?></div>
<?php
  }
} // categories_image
?>
<div class="clearBoth"></div>

<?php
// categories_description
    if ($current_categories_description != '') {
?>
<div id="indexProductListCatDescription" class="content"><?php echo $current_categories_description;  ?></div>
<?php } // categories_description ?>


<!-- you could put custom HTML here (affects all special categories) if you don't put it into the category description (for individual categories) -->

</div>

EDIT:
Winmerge found the above for me (not me)