(I tried to pick different PLs than russ if I could think of one, though I admit I didn't know of Yorick or Z++)
JFYI, FORTH is now usually written Forth. (Like LISP is now normally written Lisp.)
I'm guessing Trevor and rtm could manage about half the alphabet. pg, not a chance, he's too much of a language bigot.
I'd be lucky to get through maybe five without consulting a reference of some sort.
(Being a language bigot doesn't constrain you too much if your favorite language is a language-family.)
Once again, age and guile beats (relative) youth, innocence, and a bad haircut.
Of course, in the reply page, it's still showing up as "Touché".
Seriously, they're all real single-letter languages (Google for "[letter] programming language" and wade through the results).
I knew of only about 5 of them already (B, C, D, E, K). I couldn't find real languages for H, I, O or X.
Python, PHP, Perl, PostScript, PDF, Pascal, Pict, Pike, PL/1, Prolog.
Don't you love IBM... Programming Language 1... Operating System 2...
A: Ada, B: B, C: C, D: D, E: Erlang, F: Forth, G: Gwbasic, H: Haskell, I: Io, L: Lisp, M: Miranda, N: Newtop Script, O: OCaml, P: Perl, Q: Qbasic, R: Ruby, S: Scheme, T: Tcl, U: ?, V: Visualbasic, Z: ?, X: ?, Y: Yacc, W: ?, K: ?
I guess that's 19-21 out of 26, depending on the exact rules.
(If not, new challenge: lisp dialect for every letter of the alphabet.)
This leaves H, Q, R, T, U, W, Y, and Z, of which I can supply Qi ( http://www.lambdassociates.org/ ) and T ( http://mumble.net/~jar/tproject/ ). Bringing the list of unnamed (for me) to:
H, R, U, W, Y, Z.
That's the best I can do. Anyone else?
Q is easy - QuickBasic, under the same theory as V.
Whitespace - good call! We couldn't think of a W.
Keith Packard has been working on it for a while...