Everything you see there were indexed by swish. It's made for Web sites. Titles are extracted from HTML files and appear in the search results. You can also search for words that exist in HTML titles, META tags, comments, and emphasized tags, and 8-bit HTML characters can be indexed, converted, and searched. It's fairly nice on disk space and is pretty fast.
Index files consist of only one file, so they can be transported around and easily maintained.
You can fix the source. Although it's not in the public domain, I am always more than happy to integrate contributed code into the distribution. Please note the license concerning its use .