I was getting tired of scrapper bots hitting my site and decided to create a little project called Bot Stop. I noticed that Drupal has IP banning capabilities and thought that it would make a good addition to their arsenal of modules.
It works quite simply. Create a trap for spiders (crawl bots) that ignore the robot.txt file and ban them. Keeping information about the perpetrator on the system as well for later analysis. I am hoping to include some spam prevention techniques into this project as well.