I started this project as a convenient way to interact with the Switch over the network. Simply run the provided .nro file included in this post and connect to your device via port 5050 to access a Unix-esque shell. A full list of currently-supported commands can be provided by typing "help" at the prompt.
First ensure that you have the "telnet" client installed on your local machine (it may or may not be bundled with your base distribution). For Mac users, I recommend installing the client via the Homebrew package manager. Then, connect in via:
$ telnet [IP address] 5050
The built-in Windows telnet client does not play nicely with nxsh, so I recommend installing PuTTY. Note that connecting via a "raw" connection instead of a "telnet" one will avoid a pesky "command not found" message upon initialization of the shell. The telnet protocol sends some garbage text as it's negotiating the connection, so if you want a clean-looking shell, ditch that and go for a raw socket.
In Progress/Future Plans
Right now, there are a few big features under development. Firstly, I'm working on a set of fetch commands to retrieve files from remote HTTP/FTP servers. More ambitiously, I'm developing a shell interpreter so that basic scripts can be developed and run on the Switch, as they would under bash/zsh for example.
I'm always open to feature requests, so don't hesitate to let me know if there's something you'd like to see included in the next release!