So what is a "Tag Coud"?

Put basically - it's a collection of words or phrases put together in a module or box on your website, this jumble of words / phrases are displayed in various sizes and formats and each one is linked to a speicific page on your website.

If you scroll down this page you will see a blue section at the bottom, this blue section is this website's tag cloud, each keyword is automatically linked to the search function of the site so that when you click on a word you are taken to a search results page for that keyword.

Now I don't totally understand the SEO boost that you get from a tag cloud - I think it has to do with providing the search engine spiders with a keyword link that goes to a very keyword rich search results page and then these results are targetted for that individual keyword. It could also have something to do with boosting the number of keyword rich pages in your website - if you have 50 words in your tag cloud then the spiders see each keyword link (and the resulting search page) as a new page and index it.

If you have a static website (a website constructed of single HTML pages) then I think it would be quite difficult to setup and maintain a tag cloud, but if you use a script such as Joomla, Wordpress or an ecommerce script such as ZenCart or OsCommerce then there are plug-in's available that allow you to add a tag could almost instantly... All the keywords and their links are generated automatically by the software.

I cannot recommend tag clouds enough - I have seen great results in the SERP's (Search Engine Ranking Position) for website's using tag couds, this website was nowhere in the results 12 months ago due to the competative nature of my business, but since introducing a tag cloud I have seen huge boosts for certain keywords (try searching Google for Business Website Development)