I have been playing around with the Janowski-Indian (1.d4 Nf6 2.c4 d6 3.Nc3 Bf5!?) of late and have to say it is a lot of fun. Most of all, it tends to get me time on the clock against opponents who have never seen it before. It's not even mentioned in most 1.d4 repertoire books, including Angus Dunnington's "Attacking with 1.d4" and Richard Palliser's otherwise excellent "Play 1.d4!" I had an interesting game with the line against Greg Tomkovich in the KCC Summer Tournament, which I basically repeated against NM Mark Kernighan in the recent five-minute tournament, though in both cases I was really going out of the "book" to make the Janowski fit with my 1...Nc6 Repertoire.
In looking through Eric Schiller's Janowski-Indian e-book (which I recently downloaded), I noticed that there are a lot of games by Mikhail Tal with the line, which he used during the 1960's and 1970's as a way of avoiding the Saemisch and the Four Pawns Attack in the King's Indian. Basically, if White played an early Nf3, Tal would go into the King's Indian (1.d4 Nf6 2.c4 d6 3.Nf3 g6) but otherwise he chose the Janowski. I've collected Tal's games with the line, and he played enough of them that they basically represent an excellent introduction to the system.
You can view Tal's Janowski-Indian Games online or download the PGN file.
Janowski-Indian Defense Bibliography
Graham Burgess, 101 Chess Opening Surprises (Gambit 1998)
Recognizing that many players use the Janowski-Indian as a system for transposing to the King's Indian, Burgess recommends 1. d4 Nf6 2. c4 d6 3. Nc3 Bf5 4. Nf3 Bg7 5. Ng5!? which will force through an early e4 and present the Knight with other retreat squares than the more typical 5. Nh4 does.
Eric Schiller, The Janowski-Indian Defense (Sid Pickard e-book)
There appear to be several older paper versions of this book on the market, but his e-book is probably most useful since you will want to check his analysis yourself rather carefully. This is the most complete coverage of the opening available in print. The text files that make up the book are practically worthless, but the PGN analysis is very useful and seems generally good.
Jouni Yrjöla and Jussi Tella's, An Explosive Chess Opening Repertoire for Black (Gambit 2001).
In Chapter 31 of this book (pages 240-252) the authors offer a basic repertoire version of the Janowski. They generally make good recommendations but occasionally leave out interesting ideas (such as 1.d4 Nf6 2.c4 d6 3.Nc3 Bf5 4.Nf3 h6!? which they do not mention but which Schiller offers as the main line). Overall, though, I think this is an excellent book and they do a great job of representing this system by focusing on Black's most active choices.
Norman-Janowski, Hastings 1925
An early version of Janowski's Old Indian line.
Levitt-Day, London 2005
A recent outing for the defense.