Small and useful assembly programs

Excellent historic materials. A more "modern", if less clever grab-bag of code is asmutils:

http://asm.sourceforge.net/

If you want to see master-level x86 assembly code; google the stuff by Terje Mathisen. He was a freak programmer that won every asm optimization contest throughout the nineties. He worked on Doom and some other id titles. Lately he has been advising Intel on x86 architecture and optimization! (Yes, he trains Intel designers on how to best optimize for their own platform.)

Please don't use this unless you are actually writing code for the 8086. For example: the NOP instruction in your assembler will result in the same opcode with less work. Why write the XCHG if you don't have to? Hell, at that point it's probably faster to write the 0x90 straight into the obj code.