Modern search engine indexing techniques have been designed to be hostile to artificial influences on results rankings.
Google, the king of the search engines, uses technology they call PageRank to index and rank sites:
We've had a few issues come up lately, though, where people were concerned that particular pages didn't come up as a result of particular search queries, even though the words in the search query were nowhere to be found on the page. It is important that the words that you would expect your site to be found by actually appear in the text of the page.
I did insert a cheat in the 'Role and Mission' page in the 'About UNL' subsite just today ... it's inline and a hack, though, and I wouldn't advise it as a general rule.
If you scroll to the bottom of http://www.unl.edu/unlpub/special/aboutunl/roleandmission.shtml
, and highlight the text after 'continue to Teaching, Research and Service,' you'll see a few keywords.