Maxthon (free) is an alternative Web browser best described as an Microsoft Internet Explorer skin, and in fact requires IE to be installed in order to work correctly. However, Maxthon is so different from IE as far as features and add-ons, that it's odd that Maxthon International Limited tied it in with IE in the first place--a quirk that no other major browser shares. According to Maxthon's blog, it uses the Trident layout engine, just like Internet Explorer, and therefore should have increased compatibility in those few draconian Web sites out there that still require IE to function. Maxthon is extraordinarily popular in China (more on that later) and boasts over 200 million downloads.
Unlike most modern Web browsers, the current version of Maxthon isn't Webkit-based. The upcoming version 3 promises this design, which will bring it in line with its competition, as well as allowing it to score 100 on the Acid 3 web standards test. It's a good bet, though I can't be sure, that the new version will not require IE at all, since IE is still Trident-based and Maxthon will be Webkit-based.
Maxthon is notable because it goes to extreme lengths to be customizable. It has numerous addons available, all created by the Maxthon user community. Unfortunately for us, due to its focus on the Chinese market, many of these addons have descriptions written in Chinese only. Some have English translations, and some do not. If you can power through the language barrier using a service such as Google Translate, you can install add-ons that will do things like check Gmail for you and send you notifications of new e-mails.
Maxthon takes up very little memory and CPU, especially compared to Firefox. With a whole row of tabs open, Maxthon only took up 66 megabytes of RAM, compared to 246 megabytes for a similar Firefox setup. Maxthon also includes an ad-blocker standard, which offers a welcome respite from the proliferation of advertising across the Internet, especially audio Flash-based ads, the worst kind. Other browsers require a separate install of AdBlock to do so.
Other than the language barrier, Maxthon has a lot going for it. When version 3 arrives, it will have even more to recommend it. It's free and small, so if you're fed up with your existing browser, take it for a test drive.