First there was the failure of MediaMax/TheLinkUp, which was based on the idea of pairing online storage with social networking. In its wake comes Wuala, a new service from Zurich-based Caleido that pairs a similar plan with some unique technologies and capabilities.

One reason Wuala stands out from the crowded field of online storage is that it's based on Java. This gives it some of the advantages of desktop applications and of Web apps. Like a desktop application, it can perform tasks such as encryption using the local machine's hardware, rather than remotely on a server. Like a Web application, it can be launched from a browser, and requires no installation, meaning it will work on public Internet stations.

Wuala's creators made security a priority: Users' passwords are not even stored on the service. But there's a corresponding drawback, however; if the user forgets his password, even Wuala employees cannot retrieve the data.

"After more than three years of development and ten months of testing in closed alpha, we are very proud to release Wuala to the public", said Dominik Grolimund, Wuala's chief executive. "Our alpha users, who are storing and sharing millions of files, have given us tremendous feedback....We believe that Wuala is the right tool for millions of people to securely manage and share their files online."

Wuala users can contribute unused local storage in a grid architecture similar to what the SETI@home project does with CPU cycles. Contributing local storage to Wuala results in a larger online storage allowance. For each 10 Gbytes contributed, a user earns 1 gigabyte of online storage.

In terms of social features, the service offers file sharing, shared folders, groups, public folders, coments, notifications, and even chat. The public file sharing service resembles a peer-to-peer network in some respects, but all data is backed up on Wuala's servers, rather than being completely decentralized. Friends can be invited by importing Skype or Facebook contacts, or simply entering email addresses.

Accounts include 1 GB of free storage, which users can augment either by contributing local storage space or by purchasing it: 10 GB costs $25 per year, while 50 GB can be had for $95 per year. The free accounts display ads along the side of the window, which don't interfere too much with the main content view. For the really high rollers, a terabyte will set you back a cool grand per year.