Home automation depending on who entered the home

I've been very unsatisfied with X10-based automation systems. I've installed a bit of it in my home, and find them flakey. Smarthome's Insteon is a combo powerline/RF system that at least should be less flakey than X10. This is what I will probably try next myself, since it's backwards compatible with X10 and fairly inexpensive.

Beyond that, there are Z-wave systems like Leviton's Vezia RF+ which look pretty interesting, but they're pricy. And I hear people say great things about UPB products, but again, they cost about twice what Insteon goes for and are powerline only. In my house, I think an RF component is a good idea because each half of my house is on a separate electrical box. Insteon also makes every component a repeater, which is helpful in my house again because there are some walls filled with concrete. For me, anything that can repeat a signal is a good thing (at least I hope).

One complaint (~2006-2007) with Insteon was reliability of the devices themselves, but I understand that this has improved.

My experience researching home automation is that you can get excellent solutions by spending a very large amount of money (tens of thousands of dollars). For reasonable money, there's no one great answer, but there are answers that work pretty well. My suggestion is to build out slowly so you don't sink too much money into a single solution before finding out what really works in your house.

What you're looking for is home automation. X10 is probably the most popular technology system for this, but that Wikipedia page lists a number of alternatives.

To address your specific areas of interest:

LED lighting

There may be pre-built solutions out there, but as you're already writing custom software, you may want to look into using something like the Arduino platform to control your lights. Done correctly, you should be able to get the effects you're after. I found a tutorial about how to do a simple LED system that may be useful.

Speaker Control

There are actually a number of systems out there for home media distribution, such as Linux MCE (it took awhile to load that page when I wrote this, but it did load without timing out). You may be able to use one of these, or work some of the code in from one to duplicate the functionality (MCE is open source). The most simple solution is to use small appliance computers that run a very lightweight Linux solution (like MCE) that stream from the base computer. There are actual streaming devices out there, but I'm not sure how well they would integrate into your automation/control software. If you literally just want to run speakers, you'll need multiple sound cards in the base computer to differentiate between the feeds.

Automagical Applicances

This is where the home automation tech comes in. Using something like X10, you have the ability to flip switches, monitor their status, etc. There are appliances out there that will talk some of these languages, allowing you to control them remotely. A quick search turns up an Engadget article pointing out LG Thinq devices that are accessible via WiFi and ZigBee. If you program your software to speak ZigBee, you should be able to integrate these appliances. Given the number of different protocols out there, you'll probably want to find your devices, try to settle on devices that use one protocol, and then write your code to speak that protocol, but you can also work with multiple protocols if you don't mind developing for each. I believe Linux MCE supports a few of those languages, and since it's open source, you can expand it to support whatever you'd like.