nsL is a new C-like programming language for writing NSIS installation wizards (http://nsis.sourceforge.net). The nsL assembler takes nsL code and translates it into original NSIS script which can then be compiled.
Flasm is an assembler/disassembler for Flash actionscript bytecode.
Using flasm, script authors may learn how actionscript compiler and Flash Player virtual machine work, and tweak the compiled bytecode in SWF files for performance.