No time to rest on their laurels. At least not for Dropbox, the file storage and sharing company, which recently launched a major redesign that includes a new photo viewer and better file management. The company’s innovate aggressiveness shows that the most successful web 2.0 companies, like Facebook, Google, and Dropbox itself, must constantly innovate to stay competitive.

Dropbox’s new redesign intends to simply life for its users by making file sorting and management easier. In addition to the new photo viewer, the new Dropbox has an action bar, which lets you sort files by name, date, size, and type. The user can move, delete, rename, or download the file right there or right click on it to perform these functions, like in Microsoft Explorer. That makes the Dropbox system increasingly familiar to legions of Windows users, an innovation that is likely to pay off in the long run.

The technology world’s other top companies also work hard to maintain an innovative edge on their competitors. For example, Facebook is constantly changing its profile pages and user settings to add new features. Just this week, the company rolled out a whole new set of features for applications, which will allow users to add photos, sync locations, and tag people from any non-Facebook app once they grant privacy permission. That continues its trend of rapid, consistent innovation: back in 2010, the company rolled out a comprehensive set of changes to the site’s profile page and structure.

Presumably, sometime in the near future, Facebook will again revamp itself to stay ahead of the game. After all, the poster child for resting on its laurels is MySpace, the social media site Facebook displaced as the industry leader several years ago. Facebook executives are well aware that MySpace’s demise was closely related to its failure to innovate and will work hard to avoid a similar fate.

But it is Google’s recent innovation that has grabbed the most recent headlines. The company completely revamped its privacy policy last month, to a mix of admiration and consternation from technology commentators and users. The new policy shares user data between all Google services, which reduces the privacy of the user (because, although Google is not collecting new types of data, it will have a much more complete picture of each individual user) but also helps the company provide better targeted web searches, You Tube videos, ads, and more.

Privacy controversy aside, the new policy clearly improves Google’s ability to collect data on users and provide a more targeted, personalized experience. It represents the company’s trend of dynamically innovating to stay ahead, constantly tweaking its search algorithm and adding features over time like Gmail, Google Wave, and Google +. Some have succeeded (Gmail), failed (Wave), and are still a work in progress (Google +) but the main point remains clear: constant, rapid-paced innovation is the key to success in the web 2.0 world.