This is from the August 1974 One Hand Clapping sessions with Geoff Britton on drums. (Thanks to cb70 for this tip - even if it does make the timespan I gave in the torrent's name inaccurate.  )
Beware My Love (Instrumental, complete acetate version)
Beware My Love (uncomplete version)
Must Do Something About It (Paul on vocal)
She's My Baby (Take 1)
She's My Baby (version 2)
Silly Love Songs (without strings or horns)
The Note You Never Wrote (without strings)
Time To Hide (instrumental)
Wino Junko (rough mix)
These tracks date from the January-February 1976 Wings At The Speed Of Sound sessions.
Richard Cory
This is a live in-studio rehearsal from September 1975 - more from this session has surfaced and will be seeded very soon.
Mull Of Kintyre (count-in)
Not very different from the released version, recorded in August 1977.
Daytime Nighttime Suffering (early version)
Dates from January-February 1979.
Take It Away (monitor mix)
What's That You're Doing (rough take)
Newt Rack (instrumental)
These tracks are taken from the Tug Of War sessions at Air Studios in London and Montserrat in March 1981. Newt Rack was recorded on March 11, 1981 and is a slightly aimless instrumental with an appropriately whimsical throwaway title (get it, New tRack? I didn't either until cb70 mentioned it).
Choba Medley (Part 1)
Choba Medley (Part 2)
These two tracks contain excerpts from all the tracks recorded in the July 1987 Ñíîâà â ÑÑÑÐ sessions. This includes interesting but frustratingly incomplete snippets from the unreleased versions of "Cut Across Shorty," "No Other Baby," "Poor Boy," "Lend Me Your Comb" and "Take This Hammer."
And that's what's surfaced thus far. There may be more yet to come - Madinger and Easter mentioned the Trevor Jones collection including a tape from the Holly Days sessions. But even if this is all we get, it's still a major find. For me, Paul's version of "Must Do Something About It" alone is worth the price of admission - which is, of course, absolutely free. 
 

 However, that torrent was really just the tip of the iceberg - much more fascinating uncirculated material has surfaced from the same source, and again I've encoded them to FLAC and am uploading them here to spread this material freely. (That last word is important - there is news through the grapevine that this material is being pressed up by enterprising bootleggers.
Again, I'll try to provide some background on these tracks through the information given in the file names, the mentions of the material in Madinger and Easter's wonderful book Eight Arms To Hold You, and I'll probably make a couple of educated guesses based on what the tracks themselves sound like.
Another Day
Hi Hi Hi
Both of these are taken from acetates, and don't sound notably different from the released versions.
01 Little Woman Love / C Moon
03 You Gave Me The Answer
06 Live And Let Die (Part 2 working Session)
These tracks date from the early September 1975 Elstree Film Studio rehearsals for the Wings UK tour later that month. Madinger and Easter mention three cassettes in the Trevor Jones collection from this era, named "1975 Tour Setlist," "Tour Rehearsal 1975," and "Day 2 Elstree, 1975." It's hard to tell which tracks are sourced from which, but it does seem (through the track labeling as well as the sonic quality) that there are 3 different sources for these tracks. This seems to be musically looser, so I am (very!) tentatively going to name this one "Tour Rehearsal 1975."
Junior's Farm (Version 1)
Junior's Farm (Version 2)
Let Em In (Take 1)
Little Woman Love / C Moon
Old Man River
Soily
Stealin
Suicide
More Elstree rehearsals. Since Soily and Junior's Farm are more developed, I'll go out on a limb and dub this one "Day 2 Elstree 1975." Let 'Em In wasn't performed during that tour, and this runthrough seems to be mostly to familiarize the band with the song's structure. Old Man River and Stealin' are loose jams, the latter of which is a song Denny was quite fond of - he also performed it during the October 1980 rehearsals on the When It Rains It Pours disc. 
01 Soily
03 Picasso Last Words / Richard Cory
04 Bluebird
05 I ve Just Seen A Face
08 Yesterday
10 You Gave Me The Answer
11 Magneto And Titanium Man
11 Medicine Jar
14 Go Now
16 Letting Go
18 Live And Let Die
19 Call Me Back Again (Incomplete)
33 Listen To What The Man Said
35 Hi Hi Hi
From the track names, it's probably fair to assume two things: this is the "1975 Tour Setlist" tape and the rest of the tracks are probably out there somewhere.
Did We Meet Somewhere Before
From early 1978, not too different from what's been bootlegged before, although it might be a little cleaner than what's previously circulated.
01 Reception (Long Version)
02 Cage (Instrumental Backing Track)
03 Getting Closer (Instrumental Backing Track)
06 Rockestra Theme So Glad To See You Here (Instrumentals)
These Back To The Egg outtakes could be sourced from the early 1979 rough assembly cassette Madinger and Easter mention. The track numbers given also hint that there may be more from this cassette yet to come.
Fabulous / Teddy Bear
Madinger & Easter report three cassettes labeled "Wings Rehearsal 1980" as part of the Trevor Jones collection, and that they may contain Fabulous and Teddy Bear, in addition to In The Midnight Hour, Tears Of A Clown, Ain't That A Shame, Oh Boy, I'm In Love Again, Your True Love, and Lend Me Your Comb. If this track is any indication, the rest of those covers are very rough jams.
Momma's Little Girl (Intro)
Momma's Little Girl
Take It Away
No Values
Denny's Song
These are also likely from a "Wings Rehearsal 1980" cassette. These all seem to be from Pugins Hall in Kent (the site of the aforementioned When It Rains It Pours boot), and seem to be rehearsals in earnest for a Wings album that never came to fruition. Take It Away has been dated as October 1980, while No Values is from November 7, 1980. Denny's Song was later attempted in Montserrat in February 1981 with Paul, Denny & Dave Mattacks, but this version is a rough run-through with the rest of Wings. At the end of Take It Away, Denny reports a car accident up the road - are there any records of automobile incidents in Kent in 1980 to give this track a definite date? (Cheeky, I know.)
That's all I know of that has surfaced thus far, but keep your fingers crossed for more to appear - there's definitely more out there.

 
01 Venus And Mars / Rock Show / Jet
02 Let Me Roll It
04 Spirits Of Ancient Egypt
07 Blackbird
08 Lady Madonna
09 The Long And Winding Road
32 My Love
34 Band On The Run
These tracks belong to the previous set of September 1975 Wings rehearsals.
01 A Love For You
07 Waterspout
These two tracks probably are taken from the "Cold Cuts, 1980" cassette Madinger