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
Imlib2script: a scriptable vhook by Víctor Paesa
vf_imlib2: a libavfilter filter by Víctor Paesa
File concatenation by Wolfram Gloger
"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.
PiP (Picture in Picture): a vhook filter by Mihail Stoyanov
See this post  to see what is missing to get it into SVN.
Electronic Arts Formats demuxer/decoder by Peter Ross
http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2007-October/036938.html The format demuxer modifications and the EA video codecs have not yet been applied to FFmpeg.
Experimental MSVC port by Ole André Vadla Ravnås
Code in the bazaar branch at http://people.collabora.co.uk/~oleavr/OABuild/bzr/ffmpeg/
H264 encoder by Jori Liesenborgs & Panagiotis Issaris
DTS/AC3 in wav autodetection
http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/49812/focus=49909 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
Bink Audio decoder by Peter Ross
G722 decoder by Chas Williams
It is basically an adaptation to FFmpeg of the SirenDSP decoder.
Chinese AVS video encoder by Stefan Gehrer
Lossless msmpeg4v3 to mpeg4 transcoder
Fixed point cook decoder
GDI screen grabbing for Win32
There are two implementations in the thread above.
RealAudio SIPR @16k decoder and demuxer by Vladimir Voroshilov
Expected to work with FFmpeg r15192