I have a suggestion for documentation about tar (man, info). I just learned today that when root uses tar the ownership of untarred files will by default revert to the user who tarred the file in the first place. When downloading a tarred binary, that could be a problem because the uid for the files might not correspond on different systems. The man page should contain a sentence or two about ownership of extracted files. The info pages contain a short paragraph about it under "option summary", (--owner=USER), but I think it needs more prominent mention. Imagine my frustration when root was untarring something and all the untarred files belonged to a user I hardly used anymore.
info tar `--no-same-owner' When extracting an archive, do not attempt to preserve the owner specified in the `tar' archive. This the default behavior for ordinary users; this option has an effect only for the superuser.