TP-Link TL-WR703N

I know this isn't strictly Ham Radio but it could be useful for HSMM.

These units are around $24 on ebay, shipped from China.

Found this on Hackaday not too long ago. Basically this device is meant to be a little 3g travel router. You can plug in a 3g USB adapter and share that Internet connection to multiple devices over wifi. It also supports ethernet. Of course, the unit I bought had a Chinese GUI so that might have been a bit hard.

Fortunately, OpenWRT has been ported to this. Here are the instructions to install it: http://wiki.openwrt.org/toh/tp-link/tl-wr703n

You are looking for squashfs-factory.bin. I wish I could remember where I read how to flash this with the Chinese GUI. Here's where you need to go. Login to the GUI at 192.168.1.1 with admin/admin as username and password. Then on the left-hand side, scroll to the bottom and pick the last link. Then when the sub-menu appears, pick the 3rd link down. There's a long textbox area with a button next to it, if you click that button then you can pick the image you want to flash it with. Then click the other button on the screen to start the flash. It will take several minutes. Once it is done you won't get a webpage back. Plug into the unit with an ethernet cable and then telnet to the default IP address of 192.168.1.1 and set a password for root. Once you do that it automatically disables telnet and enables ssh. You can still use telnet until you log out though.

Here are some links that I'm reading about this so far:
http://wiki.openwrt.org/doc/howto/firstlogin
http://wiki.openwrt.org/doc/howto/basic.config
http://wiki.openwrt.org/doc/uci/wireless
http://wiki.openwrt.org/doc/howto/internet.connection
http://wiki.openwrt.org/doc/howto/clientmode#problem.using.standard.client.mode

You can install a web interface again, I haven't made mine work since I got it installed yet. I will be making another blog post on this. It defaults to Access Point mode when it first comes back up. I set mine up to run in client mode connected to my existing Wifi in order to give it access to the Internet so I could download packages on it.

There are people tapping into the GPIO (general purpose input/output) lines built into this device. So for $24 you can get a 400mhz linux computer, with Ethernet, Wifi and USB ports and several GPIO that is about the size of a new package of Post-It notes. It also uses only about 100ma as well. Beyond HSMM, this could also be handy for use in remotely controlling radios, maybe with a usb sound card you could even do something like echolink on it.

I hope to read about what others are doing with it. My focus is more on using it to setup home automation sort of things. I'm waiting on some solid-state relays and I plan on using one to control the lights in my garage, as well as giving me a real-time readout of the garage door's status.