Simple-to-use API-controllable LED light(s)?

Question

I'd like to have a simple LED light that I can control from my computer (2012 MacBook Pro). I've heard of Kickstarter projects like blink(1), but I don't want to have it stuck right up against my computer. If anyone has experience with these, I'd love to here it.

Ideally, I'd like to have three or four of these that are individually controllable so that I could make a 'flowchart'-type thing for deployments. For example, a simple Capistrano Rails deployment:

• One light for a good connection to the server
• Another light for a good pull
• One for migrations and asset precompiling finishing
• Another for complete success of everything

I would write the code to make all this happen, of course. I just need the hardware.

Requirements:

• Be able to output some noticable amount of light.
• Since I'm going to be using a few of these, they should be individually addressable and the addresses remain consistent over time.
• Work over, at most, a single USB port with an expander. I don't have a whole horde of USB ports to use. Bluetooth and wall-power would be even better, but that's probably pushing the price up.
• Have a sane API, ideally something that can be run in bash.
• Work with OS X / Ubuntu. OS X is a requirement, Ubuntu would be a plus.
• Be under $20 each. Ideally much, much less

Nice-to-have:

• Colored, but that's not a requirement. A single white-or-yellow color is fine.
• Preassembled. Solder scares me, but I'll use it if I have to.

Answer 1

I have a BlinkStick Square. They have a large variety of products (including an enclosure for my Square that I just noticed).

The Square has 8 LEDs and each are addressable individually. The Square comes pre-assembled. There are other products that provide you with the parts so that you can build it.

The API supports a number of languages (including Python and Ruby). You can also control it remotely by connecting to the BlinkStick web service.