BigAtticHouse (my company) been working on a search tool integration for Lotus Notes and our VectorSpace Database (VSDB) solution.
VSDB provides high speed, scalable search capabilities for your project, working alongside your Lotus and SQL back-end. Instead of a boolean match like SQL, it finds similarity matches with a score of 0 to 1.
http://www.bigattichouse.com/vectorspace.html
If your company might be interested in joining our limited beta and receive significant discounts upon purchase when the beta is over, please contact us on the above web page, and mention the limited beta. (or respond to this post).