2. Yes, weighting titles higher than content makes sense. There was something missing from my post, so that part didn’t make much sense. See next point…

3. Adding Boolean search is pretty simple. Only still using weighting is a little bit tricky. And for some reason I only posted part of it and messed the example for ft_min_word_len in my comment. Should have been like that:
>>>
Boolean searching has two deficiencies: 1) results are not sorted by relevance and; 2) no method by which to weigh certain columns. There is a way around both of these problems. For example, if I have a table of articles and want to weigh the title more heavily than the text, I can do the following:

S ELECT *, ( (1.3 * (MATCH(title) AGAINST (‘+term +term2′ IN BOOLEAN MODE))) + (0.6 * (MATCH(text) AGAINST (‘+term +term2′ IN BOOLEAN MODE))) ) AS relevance FROM [table_name] WHERE ( MATCH(title,text) AGAINST (‘+term +term2′ IN BOOLEAN MODE) ) HAVING relevance > 0 ORDER BY relevance DESC;

Here we artificially manipulate the relevancy score to give title more weight by multiplying by the constant 1.3. In the above query, it doesn’t seem to matter whether I have 3 fulltext indexes or just one comprising the title and text columns. From my testing, the results appear to be the same.
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4. The minimum length defines how short a word may be to be used for fulltext search. MySQL default is 4 characters, but you can change it. It's the option ft_min_word_len in the MySQL config; you can easily get the setting with php using mysql_query(“show variables LIKE ‘ft_min_word_len’”). A fulltext search for "Windows xp" would ignore "xp" because it is less than 4 characters. I guess you can see why it might be useful to allow mysql to search for short words.

5. Stopwords are words that should be ignored in a query. Every language has words that don't really count for relevance. For the english language a (possible) list is here: http://www.textfixer.com/resources/common-english-words.txt. The easiest thing is to remove those word in php (it's also possible to give MySQL a stoppword list, but that requires direct access to these options). Assuming there was no minimal word length a query like "the search for a meaning" would find every post that has a "the", a "for" and an "a", besides the really meaningful words "search" and "meaning". Umm, hope this explanation isn't too gibberish.

I have been debating adding in Boolean Search support. It’s most likely to be in a future version of the plugin.

One thing that I have struggled with is getting better template integration. The issue is that I haven’t figured out a way to manipulate the template as well as maintain the same style of the theme.
I am considering creating a “default” option that will just manipulate the WordPress query, but give you better customisation on the output if you choose to use the template file.

Am not sure about stop words and minimum length. Do you see this being used often on your site?

I like the idea of using the fulltext option very much. Besides your plugin, only one other tried it before: wordpress.org/extend/plugins/spectacula-advanced-search/. In one respect it did it better, because it works with the default search template AND it automatically filters out any result that a certain user should not see. I think it just manipulates the original wordpress query. Reading the comments here, that is a main problem. And for me this are not only private posts, but also post marked by the User Access Manager plugin. So it would be very cool if your – in some respects more advanced – plugin would use this technique too.

Some other things I really would like to see (sorry, I’m so greedy )
- Support for Boolean Search (with sorting by relevance; I’ve got a solution I used years ago, see below)
- Support for stopwords (you could use a gettext-string that lists language specific stopwords in a comma separated list and filter them out of the search query); I know you can use the MySQL options for that, but many people don’t have access to that setting
- Check what minimum word length for fulltext queries is set > mysql_query(“show variables LIKE ‘ft_min_word_len’”) 0 ORDER BY relevance DESC;

Here we artificially manipulate the relevancy score to give title more weight by multiplying by the constant 1.3. In the above query, it doesn’t seem to matter whether I have 3 fulltext indexes or just one comprising the title and text columns. From my testing, the results appear to be the same.
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I don’t know where? Is it at the function.php?

I have one problem though and that is that I have a “members area” which “hides” some pages for unregistered, using User access manager (http://www.gm-alex.de/projects/wordpress/plugins/user-access-manager/).
The “member” pages comes up in the search results, which is not good.
Is there something I can do to exclude “member pages” in the search results?

I have a question, how I hide contact form (contact form 7- famous plugin) codes from search results?
Ex: [contact-form 1 "contact"]

Thanks.