Designing a good site map takes time and thought. But site maps are important not just for the visitor. They help your company understand and design the logic of your site. If you can explain it to the visitor, you begin to understand what is most important for the site. Not providing adequate site search.
Site search serves a function similar to that of an index for a text document.
Site search has the additional strengths of being more specific and more dynamic than the index of a printed document. While very simple sites may not require a site search, nearly all the sites we have looked at would be more usable with a better search capability. The most common mistake is to provide a product-only search. The most sophisticated sites we have seen provide a generic site search, but if the visitor types in a product name, it brings up the home page of the subsite for that product rather than a list of links. Unsophisticated sites often start with a link to obscure technical information about a single aspect of the product.