nwbintools is a machine code toolchain containing an assembler and various related development tools. It will thus be similar to GNU binutils, but no attempts are made to duplicate its functionality, interfaces, or organization.
nwbintools has been under development (on and off) since January 2007. It was written from scratch in C, and version 0.1.2 has just been released under the (revised) BSD license. Full source code is available from the download page.
At present, the tool collection only consists of the assembler - nwasm - and a simple program to dump some basic ELF object file information. However, in the future nwbintools is probably going to be extended with a new linker, disassembler, and other binary file analysis tools.
nwasm is currently x86-only, 32bit-only, and ELF-only. There are lots of other bugs and limitations as well. See the bugs page for details. The current goal is to get nwasm to work well with the code generated by the nwcc C compiler, which already works to a considerable extent because that code is very simple and doesn't use many obscure x86 features.
Hopefully future releases will support the complete x86 instruction set as well as multiple other architectures, and allow for seamless cross-assembling.