Residential VLAN discussion

I use separate VLANs in my network for different type of devices. The biggest problem from this is that AirPlay does not work across subnets, something about Bonjour using link local multicast which cannot be routes no matter what. I ended up putting the airport express and AppleTV in the same vlan as the wireless devices. Ironically UPNP works just fine across subnets as long as you enable multicast routing in your network. I have a Twonky Media server streaming to my iPad in another subnet and it works just fine. Apple made a poor design decision there if you ask me.
Using VLANs excessively can really hurt your network performance - you really should know why you're doing it if you're going to do it... just providing different IP addresses to separate things out can be detrimental to your network performance by creating bottlenecks.  In most cases in a residential environment you'll do more harm than good by introducing VLANS.  In fact, as a simple rule, the only reason to do it is if you have things on different VLANS that don't and shouldn't talk to each other and you are trying to isolate them from one another.  
For instance - if you have a 24-port gigabit network switch for instance and a router where you set up your VLANS and DHCP scopes - say you have DVR's on ports 1-4, computers on 5-12, wireless on 13-14, cameras on 15-23, and your router trunk/uplink on 24 - and you have each of those groups in a different VLAN because you like to keep IP addressing schemes cleaner... well now if your computer wants to talk to the DVR or a Camera, which are in different VLANS, you no longer get wire speed switching between the computer and the camera - instead, it has to go out port 24 to your router which will then send it back port 24 then to the camera VLAN.  This happens any time things on two different VLANs need to talk to each other - the traffic must leave the switch and go to a router to get moved from one VLAN to the next.
If you work in a big high tech corporate facility that runs high end Cisco gear or equivalent, you can get some nice layer 3 switches that can actually do some of the routing without losing so much to a router bottleneck - but those switches are generally too pricey for home use.

Unfortunately this is an area where a little bit of knowledge is worse than none at all... people think they know what they're doing but in the end just end up really screwing things up and adding unnecessary complexity. 99/100 times, a single subnet and DHCP is just fine, with either static IP's or reservations to keep things at known addresses.
I use a Cisco switch, have about a dozen VLANs configured, no noticeable performance degradation. Like I said in my previous post, the only problem I ran into is AirPlay doesn't work if the devices are in different VLANs.