What's the IP address for one's own machine?
Actually localhost in most OS'es comes from your DNS lookup table. You can set your machine ot manually link certain domains to certain IPs.
If you open up your HOSTS file on Windows or Linux, the first uncomments line will be
127.0.0.1 localhost
A side note, if you know of some annoyign banner site domains and such, you can set them to 127.0.0.1 to effectivly block all content from them as well. Here's one friendly example.
Maybe you've been browsing the internet and stumbled upon Netster, it claism to be a search engine but it's actually just an advertising site that takes over dead domain names left and right. Adding:
# Netster
127.0.0.1 at.netster.com
127.0.0.1 netster.com
127.0.0.1
www.netster.com
127.0.0.1 in.netster.com
127.0.0.1 search.netster.com
127.0.0.1 mail.netster.com
127.0.0.1 smartbrowse.netster.com
127.0.0.1
www.s2ml.org
127.0.0.1 s2ml.org
127.0.0.1
www.pzchat.org
127.0.0.1 pzchat.org
127.0.0.1
www.moolahouse.com
127.0.0.1 moolahouse.com
127.0.0.1 netster.mygeek.com
127.0.0.1
www.familyhandman.com
127.0.0.1 familyhandman.com
127.0.0.1
www.my-jobs-careers.com
127.0.0.1 my-jobs-careers.com
127.0.0.1
www.casitatrailers.com
127.0.0.1 casitatrailers.com
127.0.0.1
www.hackeredu.net
127.0.0.1 hackeredu.net
127.0.0.1 un-instraw-gains.org
127.0.0.1
www.netsterdomains.com
127.0.0.1 netsterdomains.com
127.0.0.1
www.pilrc.com
127.0.0.1 pilrc.com
127.0.0.1
www.wistalliance.org
127.0.0.1 wistalliance.org
127.0.0.1
www.pilkanozna.net
127.0.0.1 pilkanozna.net
127.0.0.1
www.realnetworks.com
127.0.0.1 realnetworks.com
127.0.0.1
www.ebix.com
127.0.0.1 ebix.com
127.0.0.1
www.wrheritage.com
127.0.0.1 wrheritage.com
Would block you from seeing any of the netster garbage if you go to a URL that died. This works great for porn sites, banner ads, etc.