Tag Cloud Zen Cart module generates Cloud of Tags, based on Zen Cart product names, Zen Cart category names, most popular(purchased) products, most viewed products, products with most reviews etc.

A tag cloud (or weighted list in visual design) can be used as a visual depiction of content tags used on a web site. Often, more frequently used tags are depicted in a larger font or otherwise emphasized, while the displayed order is generally alphabetical. Thus both finding a tag by alphabet and by popularity is possible. Selecting a single tag within a tag cloud will generally lead to a collection of items that are associated with that tag.

Tag Cloud Zen Cart module features:

very easy installation (just copy files and insert small piece of code where tag cloud will appear), step by step installation instruction included
more then 10 Tag Cloud generation algorithms available out of the box
most ordered products
most viewed products
most rated products
categories with largest number of product
categories with largest number of ordered product
etc
10 visual CSS Templates available out of the box
custom CSS support (you can customize for your needs)
multiple configuration parameters available for advanced users
Enable/Disable from admin section
Number of Tags to include in Tag Cloud
Limit to popular/large tags only
Tag Cloud sorting options
and more!
completely dynamic - no manual work needed
Supports LARGE number of products (tested with 20 000+)
3 months FREE module upgrade included
Supports Advanced SEO for osCommerce (with Zen Cart support) by MagneticOne
Supports third-party SEO links modules (must have enabled for excellent results)
What benefits Tag Cloud Mod will bring you:

New modern/fresh look - it is just visually appealing
Much better internal linking
Pages of your website will be linked better between themself which brings great SEO points
A great way to highlight products/categories/keywords that sell fo