It seems to be a popular thing for bidding directory owners to want to show an image of the site listed. I guess it helps emphasise the look and brand of a listed site. It helps viewers to remember where they had seen that sight before.

We will be using the permanent thumbnails provided by MSN. These will be static, unlike some thumbnails which only show when you hover your mouse near them.

This mod will show a small image of the listed website. It will be shown on the home page and the category pages.

I can give a fair amount of support in installing this mod.
I made this mod.
Its free

Read the tutorial here :

Zorg Links Bidding Web Directory - Blog ? Blog Archive ? How to add thumbnails to your phpLB bidding directory