Mobile browser market share
StatCounter offers a rough indication of mobile browser usage share in their Top Mobile Browsers from Sept 2010 to Sept 2011 chart, which Wikipedia has made sense of in this table.
Ranked from most to least popular:
- iPhone + iPod Touch (22.84%)
- Opera Mini (22.24%)
- Android (20.21%)
- Nokia (12.57%)
- BlackBerry (9.51%)
- UC Browser (4.71%)
Mobile browser emulators
As you rightly say, the best thing to do is test on actual devices where you can, but for the missing platforms you can try the following emulators (full list here):
To test the iPhone, iPod Touch, and iPad, you can download the iOS Simulator for Mac by logging into your developer account (requires that you register a free account).
To test Opera Mini, Android, the UC Browser, and others—such as Firefox—you can download the Android Emulator.
To test Nokia's browsers, you can download the S40 and S60 emulators.
To test the BlackBerry browser, you can download the BlackBerry simulator.
An alternative to local emulation
You may also wish to keep an eye on BrowserStack, the web-based browser testing suite, who mentioned by email that they're working on support for mobile browser testing:
We received more than 50 feature requests, few have been implemented
and the major ones on which we are currently working are:
- Browsers on Mac & Linux Operating Systems
- High Responsive Live Testing
- Mobile Platform Browsers
If they're able to offer this, it would be much easier for web developers than having to download and update multiple emulators.