Any efficient text-based steganographic schemes?
My understanding is that the three most popular approaches to "steganography using text as a cover" are:

1 Generate a completely new text by picking one word at a time from a dictionary, using the ciphertext bits to select which word.


Pick words in ways that, at first glance, look like real English sentences, using Markov chain algorithms.
Weihui Dai.
"Text Steganography System Using Markov Chain Source Model and DES Algorithm".
(2010).
H. Hernan Moraldo.
"An Approach for Text Steganography Based on Markov Chains".
(2012).
"Steganographic Markov Chains".
(2008).
Anna Lysyanskaya and Mira Meyerovich
"Provably Secure Steganography with Imperfect Sampling"
(2006). Etc.
For a given dictionary, picking words with uniform distribution gives you the most ciphertext bits per word,
but it's pretty obviously not real English text. Still, these schemes are very popular for sending raw bits over systems (like email, voice, etc.) designed for text: NATO phonetic alphabet, PGP word list, the S/KEY dictionary, the Diceware dictionary, etc.


2 Take some fixed text, and send exactly the same series of letters as in the original text, adding the ciphertext bits by modifying the presentation of that text in ways that we hope the warden doesn't notice.


Use two slightly different typefaces as in Bacon's cipher (1605).
Add space characters to the end of lines, where they are usually invisible, as in SNOW (1996?).
Vary the spacing between words; nudge the letters left-right (nonstandard kerning) or up-down.
Etc.


3 Take some fixed text, and slightly modify the words in ways that we hope the warden doesn't notice.


The receiver takes each word, looks it up in the agreed-on thesaurus; if the thesaurus shows 4 synonyms, the receiver decodes that word into 2 ciphertext bits. Nanhe, Kunjir, Sakdeo. “Improved Synonym Approach to Linguistic Steganography”. Shirali-Shahreza. "A New Synonym Text Steganography". Chang and Clark. "Practical Linguistic Steganography using Contextual Synonym Substitution and Vertex Colour Coding".
The receiver looks for certain "key words", ignoring all the other words.
The receiver decodes a few bits per sentence by noticing which of several ways (all with equivalent meaning) of arranging the words in that sentence were selected. Grothoff; Grothoff; Alkhutova; Stutsman; and Atallah. "Translation-Based Steganography" (2005). a
Etc.