I\'m looking into building a content site with possibly thousands of different entries, accessible by index and by search.
What are the measures I can take to preven
If you're making a public site, then it's very difficult. There are methods that involve server-side scripting to generate content or the use of non-text (Flash, etc) to minimize the likelihood of ripping.
But to be honest, if you consider your content to be so good, just password-protect it and remove it from the public arena.
My opinion is that the whole point of the web is to propagate useful content to as many people as possible.