SwingDJs

Here's what I would recommend to anyone looking for pre-bop jazz guitar stuff. (I was inspired by the Proper Box thread).
The big stuff:
Charlie Christian 4-disc box on Columbia, and the 4 disc live set on JSP
Django has an almost Ellingtonian volume of material. There is a complete Django series that you can get usually from Django guitar sites. I'll post a link later.
Pioneers of Jazz Guitar 1927-1938 - various - Challenge; Pretty complete Lang, McDonough and Kress
Swing to Bop: Guitars in Flight 1939-1947 - various - Hep; just fantastic gems. Pickin' for Patsy and Buck Jumpin' are clearly must haves. The early less Paul is just great as well. More crucial than the Proper Box

The rest:
Pioneers of Jazz Guitar - various - Yazoo; Some more Lang, McDonough and Kress
The New York Sessions 1926-1935 - Eddie Lang & Joe Venuti - JSP; 4 discs
Swing Guitar Masterpieces 1937-1957 - Oscar Aleman - Acoustic; the argentine contemporary of Django. Spectacular.
Electric Guitar Story: 1935-45 - various - Jazz Archives; fills in some holes.
Guitar Rarities, Vol. 1 and Guitar Rarities, Vol. 2 - various - IAJRC; some really obscure stuff, mostly in the Kress/McDonough mold.

Some other things to think about:
Shaw Gramercy Five - Al Hendrickson and Barney Kessel
Metronome / Eqsuire All Star Bands - Tiny Grimes, Al Casey, Charlie Christian, etc.
Cats and the Fiddle / Spirits of Rhythm - Tiny Grimes, others
Any original era Gypsy stuff. the Ferre's are a good start. Otherwise you're likely to end up with some very modern-sounding stuff.

Wow, I've got a lot of that stuff.

I was also surprised in listening to Andy Kirk's Clouds of Joy in the 1939+ period, you get a chance to hear a lot of electric Jazz Guitar with a Big Band.
In fact between 39 and 42 It's amazing how often an electric guitar can be heard with big bands.

Brian