projects:
; various Linux/UNIX projects written in assembly language
; of course all of them feature extremely small size
; if you're looking for source code and examples, here they are

name	short description	platform	OS	assembler
asmutils	miscellaneous utilities, small libc	IA32	Linux, FreeBSD (BeOS)	nasm
libASM	assembly library (lots of various routines)	IA32	Linux	nasm
e3	WordStar-like text editor	IA32	Linux, FreeBSD, BeOS	nasm
ec64	Commodore C64 emulator	IA32	Linux	nasm
ELF kickers	ELF kickers and tiny Linux executables	IA32	Linux	nasm
BLAS	basic linear algebra subroutines	Alpha	Linux, Digital UNIX, WinNT	gas
ASMIX	several commandline utilities	IA32	Linux, FreeBSD	gas
asm-toys	few utilities	IA32	Linux	gas
cpuburn	CPU loading utililties	IA32	Linux, FreeBSD	gas
acid	small textmode intro	IA32, ARM	Linux	nasm, gas
eforth	Linux Forth	IA32	Linux	gas
smallutils	few small utils in assembly and C	IA32, SPARC	Linux	gas

There are quite a lot of mixed C-assembly projects, like Linux kernel, GNU MP Library, GNU libc, OpenGUI, FreeAmp, just to name few. You may want to examine their source code as well for examples of assembly programming on different hardware platforms.

documentation:
; Various documents on the topic
; Some of them are mustread

Linux Assembly HOWTO

Using the GNU Assembler (GAS manuals)

List of Linux/i386 system calls: this one and this one

Digital UNIX assembly

; Articles

Startup state of Linux/i386 ELF binary

Self-modifying code under Linux

; Books

The Art Of Assembly
by Randall Hyde. Classic book; general assembly programming, for newbies.

PC Assembly Language
by Paul Carter. 32bit protected mode programming, Windows & Linux, for newbies.

Assembler for DOS, Windows and UNIX
by Sergey Zubkov. ISBN 5-89818-019-2, 637 pages, 1999. In Russian language.

Assembly Language Step-By-Step; Programming with DOS and Linux with CDROM
by Jeff Duntemann. ISBN: 0471375233, 612 pages, 2000; John Wiley & Sons

Linux Assembly Programming
by me. Not available yet.

; CPU manuals and assembly programming guides

IA-32 (x86):	sandpile.org, x86.org, Intel, AMD, Cyrix, x86 bugs
IA-64:	Intel IA-64 manuals
Alpha:	Digital Alpha papers, Digital Documentation Library, more manuals
SPARC:	SPARC International Standard Documents Repository, Technical SPARC CPU Resources
MIPS:	MIPS Online Publications Library
PPC:	Beginners Guide to PowerPC Assembly Language

tutorials:
; If you're new to Linux/UNIX assembly programming, this is where you begin

Introduction to UNIX assembly programming (Linux, FreeBSD, BeOS)

Using x86 assembly code in BeOS (NASM, linking to GCC)

Linux assembly tutorial (GAS and GDB)

DJGPP QuickAsm Programming Guide (GAS and GCC inline assembly)

SPARC assembly "Hello world" (NetBSD, SunOS, Solaris)

A Whirlwind Tutorial on Creating Really Teensy ELF Executables for Linux

links:
; Links to somehow related projects

; tools

NASM	portable x86 assembler with Intel syntax
NASM 0.98e	extented NASM version
BIEW	portable console hex viewer/editor with built-in disassembler
UPX	portable executable packer for several formats
Intel2gas	converter between AT&T and Intel assembler syntax
A2I	converter from AT&T to Intel assembler syntax
TA2AS	converter from TASM to AT&T assembler syntax
SPARC	SPARC v8 assembler & disassembler

; sites

APJ	Assembly Programming Journal
H-Peter Recktenwald's site	"The Int80h page"
Jan's Linux & Assembler page	mostly about assembly programming with libc
Bruce Ediger's page	SPARC assembly related material