Often you need to download and extract archives from the internet, e.g. to install Drupal modules. Therefore you download the archive, extract it and remove the original archive. Using modern[tm] UNIX pipes you can directly pipe it to tar; therefore you don't need to save and remove the archive.
Example:
user@host> wgetar http://ftp.drupal.org/files/projects/views-7.x-3.5.tar.gz
See the result:
user@host> ls -R .: views ./views: css D7UPGRADE.txt documentation-standards.txt (and so on)