Shoppdeveloper.com

By default the Shopp breadcrumb will display “the path you followed to get here”. And frankly, that is 
what breadcrumbs are meant to do. However this means when someone enters one of your product pages using 
a direct link, the breadcrumb will be empty. It will just show the link back to the main Shopp page. 
With this plugin installed you can use breadcrumbs that show “where you are” in the hierarchical 
structure of categories.

Shopp Default Breadcrumb Extender

Add hierachical breadcrumb to your Shopp webshop product pages.

With this plugin installed you can supply your customers with previous/next buttons on the product pages of your Shopp webshop. They will no longer have to go back and forth between category/catalog pages and product pages when browsing a category. You can translate the plugin to your own language, .pot file is included. Dutch language files are already present.
The difference between this plugin’s output and the regular Shopp ‘next,previous’ output is, this plugin’s output will stay inside the chosen categorie. So if your customer is looking at a lamp, browsing the category ‘Yellow’, the next product will also be in the category ‘Yellow’ and not just another product in for example the category ‘Lamp’.
By use of the Shopp tag <code>shopp('product','browser',"show=both&cat=$cat")</code>, you set whether you want to display ‘previous’, ‘next’, or ‘both’. Take a look at the more detailed instructions below.
By use of the settings page, you specify
<ul>
<li>the phrases used for ‘Previous’ and ‘Next’</li>
<li>to use product thumbnails instead of ‘Previous’/’Next’</li>
<li>the size of the thumbnails</li>
<li>to use predefined Shopp image-setting</li>
<li>which categories to exclude (‘Previous’/’Next’-buttons will not appear on those Shopp product pages)</li>
<li>which products to exclude (‘Previous’/’Next’-buttons will not appear on those Shopp product pages)</li>
</ul>

Shopp Product Page Browser

Add "previous/next"-product links to your Shopp webshop's product pages.

Shopp Default Breadcrumb Extender vs Shopp Product Page Browser