"`read-from-buffer'" functionality

[Joe Corneli <jcorneli@math.utexas.edu>]

I would like to get user input in the form of text from a new buffer.

(w3 does something like this when you edit a text form.)

There doesn't seem to be a built-in function for popping to the new
buffer, waiting until C-c C-c is pressed (say), and then returning the
buffer's contents as a string.

Presumably that means it isn't too hard to code this using more basic
functions, but user input on a whole is new to me and I was wondering
if anyone with more experience in these matters could give me some
tips.