One bit is a 1 or a 0. True or false.
Eight bits make up a byte. This also holds one 8 bit ASCII
character. (Sorry Unicode, that's too complicated for this demonstration.)
A kilobyte can either be 10^3 (1000) or 2^10 (1024) which can get confusing. These would hold a thousand ASCII characters.
wc says that the GNU public license that came with xmms (about 3000 words) is 17992 bytes.
Assume a small novel is 200 pages, 100 words per page, 5 characters per word, and encoded in ASCII. 200*100*5 = 100,000 characters, about 100 KB. It will fit on a floppy. (Note that this is just an estimate.)
Multiply that average by the number of volumes in your local library, and you will get approximately the size of it. (Just text, nothing else.)
The New Oxford Annotated Bible
is about 2200 pages with high word density. 2200 pages * 300 words * 5 characters is more than 3,000,000 characters. But we're still in the megabyte range.
It takes a lot of text to fill a gigabyte, but you could probably fit the text most libraries on a modern hard drive.
has public domain texts in plain text, usually a few hundred KB each.
As for audio, my general rule is that a decent 128 kbps mp3 takes about 1 MB per minute. A CD will take about 10 times that.
The Internet Archive contains roughly a petabyte of data
Hopefully some of these random facts and estimates will help.