base64(1) is useful to convert any binary-encoded file into plain-text.

	tar -c dir/ -f - | base64 > tarball.b64

With the rise of online text pastebin[0][1][2][3], sharing text has
never been so easy. Most services will reject binary input though,
so base64 can come in handy to trick them into accepting more various
formats, like tarballs, videos, …

Its older brother uuencode(1), commonly used in emails, can also be used
for this purpose.