One of the biggest advantages of Android over iPhone is widgets. Android has them, iPhone does not.
Widgets are valuable because they can provide an at-a-glance look at lots of different kinds of information and quick access to valuable apps and configuration settings.
To help you find some of the most useful widgets, I've put together my list of the top 15. The best way to way this list is in the screenshot gallery. But, you can also view it in list form below.
A couple things to keep in mind with widgets: 1.) They can sometimes hog resources, bandwidth, and battery life so you should make sure you're using a task killer to regularly refresh your open apps; 2.) Widgets can take up a lot of screen real estate and so you may need to use an alternate home screen launcher, such as Launcher Pro, to give yourself some extra space.
Android comes with a "Power Control" widget (bottom) that I've always liked because it lets you quickly toggle Wi-Fi, Bluetooth, Brightness, and more. However, I recently discovered the "Extended Controls" widget, which allows you to create a customized version of Power Control with a lot more toggle options.
2. Battery Watcher
This widget provides a battery percentage visual. Since you can't add the battery percentage to the notification icon in Android, I always anchor this simple widget on my primary home screen on any Android device. I like that it is the size of an app icon, so it doesn't take up too much screen real estate.
3. Picture Dial
This is a smartphone speed dial app that allows you to set up your most important and most frequently-dialed people or numbers based on photos. You can see the two sizes of the widget, one with two numbers and one with four. You can also stack multiple widgets on the same page. The default configuration is that you select a contact and then assign phone, text, or email to the speed dial button.
4. Analytics Widget
If you use Google Analytics to track Web site traffic, this little widget makes it easy to get a get quick glance at your traffic metrics. It takes up the same amount of space as an app icon and you can set up multiple widgets to track multiple metrics.
5. 3G Watchdog
As most people are aware, "Unlimited Bandwidth" data plans are not unlimited. Most of them are capped at 5GB. Plus, companies like AT&T are moving away from unlimited plans altogether. That means people are going to need to be more conscious of the bandwidth usage. The 3G Watchdog is a widget that can track it for you. The widget is available in two sizes, as you can see in the screenshot.
6. System Info
This widget provides a great little system monitoring function for battery life, over-heating, memory, and storage.
7. Pure Calendar
There's a built-in widget that can provide a quick glance at your calendar but Pure Calendar is far more detailed and customizable.
8. Pure Messenger
The cousin of Pure Calendar is Pure Messenger, which can provide a quick glance at your inbox. It can even integrate SMS messages, Twitter DMs, and Facebook mail.
Buzzbox offers a no-frills widget for quickly glancing at the news. There are a bunch of pre-configured RSS sources (including some good ones for tech) and you can easily add your own.
10. SMS Unread Count
The basic premise here is that this widget replaces your Messaging (SMS) icon with a widget that looks like an icon but includes a little red circle in the upper right corner with the number of unread messages you have (mirroring the iPhone UI). The app can also do this for Gmail and Phone (missed calls).
11. Last Call
This widget provides a glance at your last call, which makes it easy to redial or to call back a missed call. You can also click on the widget to go to your full Call Log.
For travelers, the FlightView widget is very handy. Rather than digging through apps or Web pages to get a flight status update, you can enter your airline and flight number into this app and it will track it for you.
As I've said before, Twitter is a terrific real-time intelligence engine. Now that there's an official Twitter Android app, there are also a couple Twitter widgets (large and small) for scanning your Twitter stream.
This is a Google widget that lets you keep track of the scores from your favorite sports teams. It shows the last game and the next game (or current game).
Pandora is a custom streaming "radio station" for the Internet age. You simply search by an artist or song and it will create a running playlist based on that one piece of information. This widget makes it easy to control Pandora, including play/pause, thumb up, thumb down, and skip-track buttons.