Under certain circumstances you may want to anonymize your scraping so that the target site is unable to trace back your IP address. For example, this might be desirable if you're scraping a competitor's site, or if the web site blocks IP addresses that make too many requests.
There are a few different ways to go about this using screen-scraper:
If you choose to run anonymous scripts from an external script, it is valuable to read through the documentation on controlling anonymization externally.
Aside from the above methods, you might find our blog posting on how to surf and screen-scrape anonymously helpful. It's slightly dated, but still very relevant.