Google is now rolling out the Android "Jelly Bean" version 4.2 system to capable devices, and there's a new feature included that is not particularly obvious, but is potentially so important to so many people that it deserves a special mention.
As most of us learn sooner or later, using smartphones and other portable devices becomes increasingly challenging as we age, given that most people's vision starts to degrade beginning as early as their 20s. Small fonts maximize information density if you have the visual acuity to resolve them. Otherwise, they can be rather frustrating.
While Android apps and the Android system itself have been getting consistently better about providing font and other sizing controls, there have still been various situations where ease of viewing has been suboptimal on small displays.
That's why I've been very pleased by the new deeply integrated zoom/pan magnification function included with JB 4.2. After being enabled, which you can do via Settings->Accessibility->Magnification gestures -- you can triple-tap virtually anywhere in the Android environment (except the keyboard and notification panel, I believe) and instantly magnify the current screen. You can then pan around and change the zoom level by touch, and drop back to normal view with another triple-tap. It's extremely well implemented -- kudos to the team responsible! [Addendum (11/16/12): If you triple-tap and hold down on the third tap, you enter a "temporary zoom" mode where you can pan around with that single finger. When you release, you'll pop back to normal view mode automatically. Very convenient for quick magnification of text, etc.]
While I'm talking about settings, regular Android users may notice that 4.2 seems to have eliminated the traditional "Developer options" such as "USB Debugging" and others. They're still available, but since a relatively small proportion of users ever need them, Google has sort of turned them into an "Easter egg" function of sorts.
To enable "Developer options" go to Settings->About phone, then scroll down to "Build number." Tap on Build number. Do it again. Keep going! After a number of taps, you'll be informed that you're getting close, then you'll be anointed with Developer status. Take another look at the main Settings menu -- the Developer options will now be permanently available.
There are other very useful advances in 4.2 as well -- more powerful camera app, gesture keyboard, and much more. Great work!