I don't know why you wouldn't want traffic (unless you're operating on limited bandwidth.) But you can use a robots.txt file to disallow certain spiders from visiting your site. MSN
currently uses Inktomi's spider to supplement their results from the LookSmart directory. So you could set it up to disallow that spider from visiting your site the next time it comes through.
Robots.txt Tutorial
Just be forewarned that Yahoo now owns Inktomi's search technology and will most likely be turning to it to power Yahoo search results in the near future when they dump Google. So if you disallow Inktomi now, you may not be showing up in Yahoo in the near future. Microsoft is currently working on developing their own spider-based engine to compete with Google and Yahoo's various search technologies.