Once you have a site that has a lot of information, your readers will want to be able to search the site for information. A search engine or search utility gives your site more interactivity with your readers and encourages them to stay longer.

You have a couple of options for putting up a search engine on your site. You can run a CGI across your entire site, or JavaScript across individual pages. You can also have an external site catalog your pages and run the search from that. Remotely Hosted Search CGIs

This is the easiest (usually) method to add search to your site. You sign up with a search service, and they catalog your site. Then you add the search criteria to your pages and your customers can search through your site.

The drawbacks to this method are that you are limited to the features that the search company provides. Also, they can only catalog pages that are live on the Internet (Intranet and Extranet sites cannot be cataloged). Finally, they only catalog a site periodically, so you don't have any guarantee that your newest pages will be added to the search database immediately.

The following sites offer free search capabilities for your Web site.

FusionBot
FusionBot offers multiple levels of search, at the free level you get: 250 pages indexed, 1 automatic index per month, 1 manual index per month, basic reporting, sitemap, and more. It even supports searching across SSL domains.

FreeFind
It is simple to sign up for this free service. It has additional features of a site map, and "what's new" pages that are automatically generated along with your search field. You control how often they spider your site, so you can be sure that new pages are added to the index. It also allows you to add additional sites to the spider to be included in the search.

Google Custom Search Engine
The Google custom search engine allows you to search not only your own site, but also create collections to search within. This makes the search more interesting for your readers because you can specify multiple sites to include in the search results. You can also invite your community to contribute sites to the search engine.

Pico Search
Add up to three entry points to your search engine on the free plan. You get email tech support, 250 indexed pages, and manual reindexing. It has nice reporting that is easy to use and understand.

siteLevel Internal Site Search
With this free service, you add the functionality of having pages that are not included in the database. Thus if you want to have a certain section private, and not searchable, you would simply list that as an excluded area, and those pages would not be searchable. The free service will index 1000 pages with one re-index per week.

See the above in action Host the Search Engine on Your Site

If you want to have more control over what is searched and who has access, then you might want to look into hosting the search engine on your own server. This will require that you have CGI or other programming language access on your site.