I recently had a client where I did some wireless scanning and aside from the heavy PC tools, I used Wifi Analyzer on my Android phone. It's a nifty little tool, but didn't always show the detailed information I wanted. So I also installed Network Info II to get the detailed network information.
What I thought would be really helpful would be a terminal to access the Unix command line and I found that with Android Terminal Emulator. While a stellar app that provides a direct command line interface, it relies on the system installed commands - so we have some file manipulation tools (e.g., ls, cd, cat). It does not provide text manipulation tools (e.g., awk, cut, grep) and handy networking tools (e.g., nc, telnet, ssh). For that, you need to install busybox.
A lot of searching indicated most busybox installations for Android required root and I did not root my phone. This seemed odd since once installed, most command line utilities don't need root to run (except things like 'ping' which only required suid). I finally found some instructions to install a "non-root" busybox and tried it. I'm not linking to it because it only partially worked - the network tools couldn't perform name resolution; a partial success.
The solution I used was BusyBox Non-Root. This little application installs busybox, creates the necessary symlinks and provides a shortcut to copy/paste the install directory into a Unix $PATH statement. You can paste that into the "Initial command" under "Preferences" in the Android Terminal Emulation app. Now, from a command line I have access to working versions of 'nslookup', 'telnet', 'ssh' and many other text manipulation tools.
The only puzzling thing I found was netcat (nc) wasn't available. Running buxybox from the command line showed that 'nc' was available in the package, so a quick 'ln -s ./busybox ./nc' solved that problem. Of course I tested it and 'nc' works too!