I heard many times, that WordpPess's search doesn't work good.
Are there any other search engines available for wordpress?
I know about sphynx, seems its a good one, but available plugins are out of date.
Search results sorted in the order of relevance, not by date.
Fuzzy matching: match partial words, if complete words don't match.
Find documents matching either just one search term (OR query) or require all words to appear (AND query).
Search for phrases with quotes, for example "search phrase".
Create custom excerpts that show where the hit was made, with the search terms highlighted.
Highlight search terms in the documents when user clicks through search results.
Search comments, tags, categories and custom fields.
Adjust the weighting for titles, tags and comments.
Log queries, show most popular queries and recent queries with no hits.
Restrict searches to categories and tags using a hidden variable or plugin settings.
Index custom post types and custom taxonomies.
Index the contents of shortcodes.
Google-style "Did you mean?" suggestions based on successful user searches.
Automatic support for WPML multi-language plugin
Advanced filtering to help hacking the search results the way you want.
There are a lot of a posts written about this, and it took me a while to figure out a solution. Google Custom Search is a great solution - if you have a google account (which you can easily get if you don't), a basic understanding of wordpress themes, and some php.
If you don't have those skills sets, there is a pretty good plugin you can use. It's not as good as Google Custom Search, but it does the job better than the Wordpress's search engine.
Hope this helps a bit.
I personally like a lot the Search Unleashed plugin. Simple and efficient. It does need a bit of patching unfortunately, because the author seems to have given up. Fortunately, the patch can be found on the wordpress forum, in this thread.