This page tries to collect some useful patches for FFmpeg that didn't make into SVN for some reason or another.
native Zlib decoder by Mans Rullgard
In the same thread, there are patches to use the native decoder in several FFmpeg decoders.
WMV3 encoder by Denis Fortin
H.263 rtp patch
http://www.voxgratia.org/bin/ffmpeg-0.4.7.patch.zip, originally at http://www.salyens.com/downloads/index.html#ffmpeg-0.4.7, now removed.
Apple RPZA encoder by Todd Kirby
Test Pattern Generator Demuxer by Nicholas George
Test Pattern Generator Demuxer by Ramiro Ribeiro Polla
PES packetizer by Xiaohui Sun
Part of the work of Summer Of Code TS Muxer
vf_imlib2: a libavfilter filter by Víctor Paesa
"mem" file protocol by Lagrange Multiplier
The "mem" protocol simply uses RAM as a source for input multimedia data, akin to how the "file" and "pipe" protocols use filesystem files and pipes as sources.
Presets/profiles for usual targets by Panagiotis Issaris
Allow to keep in a text file groups of command options, and apply them at once by specifying the target name.
Handy for iPod, PSP, or any other picky multimedia player that otherwise requires lengthy command lines.
See this post  to see what is missing to get it into SVN.
Experimental MSVC port by Ole André Vadla Ravnås
OAH Build System https://launchpad.net/oah
H264 encoder by Jori Liesenborgs & Panagiotis Issaris
DTS/AC3 in wav autodetection
http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/49812 Clean up this patch and also add detection of AC3 in wav, it is similar. Samples for both can be found here: http://www.sr.se/cgi-bin/mall/artikel.asp?ProgramID=2445&Artikel=739973
G722 decoder by Chas Williams
This patch has no licensing issues, but also contains an encoder which was basically rejected by the project maintainer.
It might be enough to resend the decoder alone to get it into svn.
Chinese AVS video encoder by Stefan Gehrer
Lossless msmpeg4v3 to mpeg4 transcoder
Fixed point cook decoder
fixed point wma decoder
http://svn.rockbox.org/viewvc.cgi/trunk/apps/codecs/libwma/ Rockbox's fixed-point WMA decoder was adapted from the decoder in libavcodec.
GDI screen grabbing for Win32
There are two implementations in the thread above.
Proper parsing of DTS-HD MA streams
G.729 decoder by Vladimir Voroshilov
MS Video 1 encoder by Kostya Shishkov
LucasArts SMUSH demuxer and decoder by Kostya Shishkov
MPEG-4 ALS encoder by Justin Ruggles
libaacplus and FFmpeg encoding patch
Bayer RGB decoder
Chromium security patches
Security/stability patches from Google's web browser http://src.chromium.org/viewvc/chrome/trunk/deps/third_party/ffmpeg/
Framebuffer input device by Giliard
Cedric's alpha blending routines
The blending routines should be moved to libavfilter where they seem to belong.