You main resource for Linux/UNIX assembly programming material is Linux Assembly :). Here are some of resources listed there. This list is cut-down and may be outdated, so please visit the site for detailed up-to-date list.
Note that several projects are not Linux-specific, and run on FreeBSD and other OSes too.
There are quite a lot of mixed C-assembly projects, like
Linux kernel,
GNU MP Library,
GNU libc,
OpenGUI,
FreeAmp,
just to name few.
Some of them use gas (sometimes with m4), the other use nasm.
You may want to examine their source code as well for examples
of assembly programming on different hardware platforms.
If you're are interested in Linux/UNIX assembly programming (or have questions, or are just curious) I especially invite you to join Linux assembly programming mailing list.
This is an open discussion of assembly programming under Linux, FreeBSD, BeOS, or any other UNIX/POSIX like OS; also it is not limited to x86 assembly (Alpha, Sparc, PPC and other hackers are welcome too!).
List address is mailto:linux-assembly@egroups.com.
To subscribe send a blank message to mailto:linux-assembly@egroups.com.
List archives are available at http://www.egroups.com/list/linux-assembly/.
Unfortunately there are no ready books I can recommend on the topic. However I'm in the progress of writing a book "Linux Assembly Programming", which /hopefully/ will be published somewhere in 2000-2001.
$Id: Assembly-HOWTO.sgml,v 1.14 2000/05/04 07:47:47 konst Exp $