I'm currently using a 17" flat screen with the PlayStation 3 and, also, for my MacBook Pro in clamshell mode. For the laptop, it is "reasonable" given that it has a similar resolution to the one of the built-in screen, but for the PlayStation 3 it simply sucks: I can only use it through the composite input, which results in very bad graphics quality. I also miss the 20" monitor I sold when I bought the MacBook Pro, which was very nice to watch videos and had lots of real screen state to work comfortably. So... I'm in the market for a widescreen computer monitor that natively supports Full HD (i.e. 1920x1080), and that brings me to the 24" world. These things are huge!

Here are some things to take into account when looking for such a monitor:

• Resolution: All 24" computer monitors (not TVs) I've seen have so far have a 16:10 aspect ratio with a resolution of 1920x1200. Some 23" ones also have this same resolution, and I can assume that slightly bigger ones also will. But to support Full HD they need a minimum of 1920x1080.
• Response time: This is the time it takes to change the color of a pixel. Usually, the lower the better to prevent ghosting, but this is hard to qualify. Each vendor advertises this in a different way, because there are multiple measures that define the response time. For example: you can measure the time it takes for a pixel to go from white to black or from a tone of gray to another tone. Some vendors will only tell you the smallest one. The best specification is when the vendor provides you all different numbers.
• Brightness and contrast: All monitor specifications will give you some numbers about the brightness and contrast ratio of it. Be aware that there are two measurements for the contrast ratio: dynamic and static.
  
• Video inputs: There is a wide variety of rather cheap 24" monitors, but most of them are very limited in the inputs they support. The cheapest one I've found so far only has an analog VGA connection; avoid those. If you are going all the way up to a big monitor, do it right and use a digital connection; otherwise the image may be blurry or unstable.
  Virtually all other ones have a single digital DVI or HDMI input and an analog one. The most advanced have additional inputs, such as two digital connections (one DVI, one HDMI), a VGA analog one, composite, component, S-video, ... In this area, just choose the one that will suit your requirements, but the more connections they have, the more expensive they will be.
  
• HDCP support: If the monitor has digital inputs — DVI, but specially HDMI — make sure it supports HDCP. This is required to watch 1080p high-definition content; otherwise, players will only output 720p, which is half the resolution. So, to use the PlayStation 3 in its full power, you must have HDCP. And I assume that some computer media players also require this... or at least that's the idea I have about video playback in Windows Vista.
  
• 1:1 pixel mapping: Widescreen computer monitors have an aspect ratio of 16:10, but game consoles and video players output video in 16:9. In terms of resolution, the monitors have 1920x1200 pixels but the video signal will only be 1920x1080. There are many monitors out there that will scale the 16:9 image to fill the whole 16:10 screen, which will distort it. If the monitor supports 1:1 pixel mapping, it will happily display the lower-resolution image on the screen without distortion, adding small black bars at the top and bottom of it.
  Now, looking for this feature in the vendors' sites is hard... if not impossible. I have not found any list of specifications that mentions it and have only been able to guess whether a given monitor supports it or not by looking at random forums around the Internet. And even then the answers are not very clear.
  
• Picture-in-Picture (PiP): This feature allows you to display two different video inputs at the same time on the monitor. One covers the whole display and the other one is shown in a window on top of it. All of this is done internally by the monitor.
  
• Vertical orientation: Some monitors allow you to tilt them vertically, thus providing a resolution of 1200x1920. I can't imagine how useful this is, but it might be nice to watch some specific photos that were taken in such orientation.
  
• Additional connectors: Look for extra USB or FireWire connections, ideally with extra power.
  
• Speakers/microphone: Some monitors include built-in speakers and/or a microphone. I personally do not care much about this because built-in speakers tend to produce low-quality sound. And with such a huge screen I assume you also want decent audio playback ;-)
  
• Built-in power supply: To avoid more clutter under your desk, you may want to check if the monitor has a built-in power supply or an external one.

So, what am I looking for? I want a monitor with: at least two digital connections, preferably a DVI and an HDMI one; HDCP support; an analog input would be nice; 1:1 pixel mapping is a must; speakers are irrelevant. I've already made my choice and, hopefully, I'll get it today :-) But on the next post I'll try to summarize some of the monitors I've analyzed.