On the home screen, I keep all the most important apps, the ones I'll use frequently, and they are in alphabetical order. On the dock I have Mail, Safari, Music, Videos, Photos and Settings. The Home screen apps include:
AccuWeather, Air Sharing, Calculator, Calendar, Camera, Clear Day, Clock, Contacts, Dropbox, Google Maps, Maps, Messages, Notes, Reminders, Tipulator and Weather. They are arranged in just four rows, leaving some space between the fourth row and the dock, rather than filling that space.
On the next page, I have games, again arranged in alphabetical order. Page 3 includes reading matter/reference materials/Pages/educational/and the wonderful The Elements. Again in, yep, alphabetical order.
Next up comes the page devoted to photography apps. Again, alphabetically arranged.
The next page is devoted to music apps and entertainment, so along with Garage Band, there's UrbanSpoon and Netflix, with, of course, YouTube.
The last and final page is made up of folders in which I have the apps that I don't use often but want available anyway. There aren't many of these, as I have found in the past that if I don't see an app icon I kind of forget that I have the app. Using folders is handy for the apps that I only need once in a while.
Periodically I shift things around if I find I'm using an app more than I'd thought I would, etc.
The backdrop for all of the apps is a very abstract photo that I took some time ago, which has a lovely, soft blending of various colors. The image on the lock screen is a much more vibrant (but again abstract) image that works nicely as well.