- Don't bother wiring coax and cat5 into places you're not sure you'll need it. What you really want is Smurf Tube ( <a href="http://www.avsforum.com/avs-vb/showthread.php?t=901909" rel="nofollow">http://www.avsforum.com/avs-vb/showthread.php?t=901909</a> ) dropped to places where you think you might want something someday but don't know how much of what you'll actually use. This is probably less extravagant now than it was before copper went sky-high<p>- The real reason you want cat-5 in every room is so that you can have PoE VoIP phones instead of crappy analog handsets. This is particularly useful if you install a linux host running the Asterisk PBX. Don't want your mother in law calling before 10AM on weekends? Filter her caller ID to voicemail while you sleep -- Asterisk is a huge geek enabling technology.<p>- I'd probably smurf tube the doorbell location and consider putting a door phone there - a speaker and mic with a button. Sometimes you don't know who it is, and you don't know if you want to answer or not. This is particularly valuable for people in the household who aren't the alpha male and might not have the ability to stop someone from entering the house if the door was unlocked. You can also tie it into your asterisk host and have it call your cell phone, telling the delivery man to leave the packages at the door or telling the unsolicited guest during the day that you _are_ home, you're _not_ interested, and they should find someone else to rob.<p>- I'd skip the whole house smart lighting thing. Having your home lighting at the mercy of something that will fail when lightning strikes it is a non-starter to me. I'd consider hand-rolling a DMX system for any media rooms, but you can do this on the low-4-figure cheap, instead of mid 5s.<p>- Speaking of lightning, there are whole house surge surpressors, and they're a good idea in my opinion.<p>- In my next home I intend to install a generator. To enable this I'd ideally have at least two breaker panels -- one with the non-critical services (dryer), one with the critical services (refrigerator, house lights) that is connected to the generator transfer switch, and possibly a third with super-critical services that is fed off of a generator panel circuit and through a UPS.<p>- A while back I saw some kind of inductive AC current sensing devices that could be installed around Romex. This, combined with a server doing other stuff would be a neat way to track key (or all) circuits in your house to watch power consumption.<p>- Security: there's open source camera server software out now that is pretty cool. If you run cat5 to the corners of your house you can elect to install cameras with IR blasters, and track people and things coming and going. Makes the video doorbell thing seem kind of silly.<p>This is all I can think of at the moment. I love this topic and could geek about it for hours... :)