Custom Xbox 360 themes
With the Xbox 360's Dashboard there are plenty of themes you can buy, but sometimes I find that they're perhaps not what I want to have. Since I imagine there's a sizeable enough community of people on The Verge with a 360 and graphical know-how I figured it might be worthwhile to provide a resource for people who might be interested in creating or finding new Dashboard themes that appeal.
The first example I can think of is this Picasa folder. At one point it was maintained by a group of users from Xbox360Achievements.org but since then it has stopped being added to. Even so it's a great resource if you're looking for some new styles for your 360. There was also nxe.weebly.com, which they also operated. From memory it had a wider selection of images but I could be wrong in saying that. In any case it is worth checking both out, since they often have some great images.
In addition, the Verge wallpapers contributed by thefryinallofus, which are downloadable from his deviantART can also be used, assuming you have a memory stick or your PC set up to stream pictures over a network.
Choosing Images on your PC
If you're looking to stream images to your 360 from your computer there are a plethora of different applications that will do exactly what you need. As a Windows user I can say more from the Windows side, but I have a little experience with things on Mac OS X. Unfortunately I know nothing about streaming from Linux, but I'd suggest something like WINE and a Windows application. Anyway, with Windows you can connect using Media Centre (if you have a machine running Windows Vista or Windows 7; for some reason XP Media Centre Edition doesn't play well), but I've always found this service to be rather inconsistent. It works some of the time, and then not at other times. Maybe it's me, but iot grows a little frustrating. In any case it can be used, if you set the 360 up as a Media Extender.
TVersity is one of the applications I've used more for this, and it works very well. Just tell it what folders to share images from and you're good to go. You can even broaden the scope a little further and stream images or videos, assuming they're in a format the 360 can make use of. In addition, it isn't particularly ugly looking and can refresh your library if there is something you want to see urgently. When you're on the 360 you simply have to go through your media devices and find TVersity. Once you've done that, then you can scroll through your images and find what you want.
With Zune, you simply have to go into the settings, enable media streaming and choose what consoles to stream to. If you can't find your own then you'll have to make it available to all 360s in the area. Considering the scale of most networks though this shouldn't be much of a problem. Enable image streaming and whatever else appeals to you, and repeat the same process of finding it on your 360. Once you've done that check for the images or other files you want to make use of.
If you're a Mac user then your only choice, as far as I am aware, is to use Connect360. It's not free but I believe there is a trial available for it. In any case it is dead simple to set up. You just choose what you're looking for, and then on the 360 look for an option marked 'Connect360'. From then on you can connect in, just like with the other applications I am aware of. Connect360 is probably the most well laid out of the three applications I've pointed out, and is straightforward enough to use and to work with.
A method that works on all operating systems, however, is to plug in a USB memory stick and move your images to it. Plug the memory stick in, copy images over, and then put the memory stick in your 360. On the console it will be called Portable Device.
Choosing Images on your Console
Once you're on your Xbox 360 Dashboard, then go across to 'Apps' on the Dashboard and select Picture Viewer under it. Select the method you've chosen. In my case that's Zune, and it comes up with the name I assigned for it. Once you're in it will load all the images for you, and you can go through them with thumbnails or as a slideshow. Once you've reached the images, find what you're looking for, and press the Y button on the controller. It will prompt you to set it as the background on your Dashboard. Say yes, and enjoy your new background. The functionality has been around for a very long time and most people likely know about it by this point but I felt it was worth bringing up along with a directory of different locations for finding images and creating your own.
16:9 template: http://alcozzi.deviantart.com/art/Xbox-NXE-Wallpaper-Template-104322594
4:3 template: http://sircob.deviantart.com/art/XB360-NXE-Standard-TV-Template-105166168
Planet Renders: http://planetrenders.net/
I'm not sure if the 4:3 template will actually help anyone, but all the same, it is there for the sake of completion and in case anyone has an SDTV. While it is a PSD, you can still use the 16:9 template if you save it as an image itself and work with it in another program. I'm sure the community can come up with some great looking templates and designs. Planet Renders can be very helpful for finding large, high quality images to use.
I would have outlined how to create images for the PlayStation 3 as well but to be honest, I don't know how. If anyone wants to explain that they're more than welcome to since I couldn't really give it a decent attempt. As for PCs it's basically a case of setting a desktop wallpaper, which could not be easier, and hardly warrants any explanation of how it is done.