Many web owners veer well away from stat packages such as AWStats or Google Analytics. They data can be confusing to the initiated. However, once you get an understanding of those stats you will see that often they hold real SEO treasures that can be used to increase your sites visitor numbers.
Keywords are always a problem. Which keywords should I use; how much competition is there for them; how many people are using those keywords? If you check your stats and AWStats if you have in on your server, or Google Analytics, both provide results based on keywords used to find your pages.
If check those results you will be surprised at what you find. Along with the keywords that you have optimized your site for will be search terms, particularly long tail, that are delivering significant amounts of traffic. If you take those search terms and work them into your long term search engine optimization strategy, you may find that more traffic is generated.
Search engines look at the search term and do a comparison with pages that have been indexed. If your content appears to satisfy that search term it will then have a good change to rank in the major search engines for that keyword phrase. The results are then published to the searcher. If you check through your pages you may find that certain terms have been used often enough that the search engines flag those terms as important (keywords or keyword phrases).
Use that accidental ranking by working those terms more frequently into your pages. Good SEO practices encourage the constant review of search terms used to find pages so that optimization can be tightened.
As a side note, there is also the problem of searchers finding your pages for the wrong reasons. Sometimes you need to go back to old pages and remove repeated phrases so they do not show up in the search results. The question is – is any visitor, even a wrong visitor, better than no visitor. If you are selling from your web pages, the answer has to be no. Your main goal should be trying to generate visitors that will lead to sales, generate leads or whatever your conversion metric might be.