Idle LANs: Three nonaltruistic ways to use your PC's spare capacity

You probably already know that you can take that desktop computer you leave on all the time and use its spare computing power to look for extraterrestrial intelligence or a cure for cancer. Swell. But suppose you're not so much into saving the world? Suppose you want to just save your data? Or make a few bucks? Check out these three services that use your PC's storage and bandwidth to serve you--not the world.

Wuala. This is a cloud storage service that you can use to save files for backup or sharing. But on Wuala, the cloud is made up of the hard disk on your PC plus those on other Wuala users' computers. Data on the Wuala network is distributed in tiny, encrypted, redundant slices among users, so no one can see another person's data. The more space you set aside on your PC for Wuala storage, the more free storage you get on the Wuala network. You can buy your way in if you don't want to share. Although I am very skeptical about relying on the "social grid" for storage, the price can't be beat. We covered the company during its closed testing period; the service is opening up to the public today.

CrashPlan. This is another storage play, but with a strong focus on backup. Unlike services like Mozy and Carbonite, where you pay a fee for access to centralized backup servers, with Crashplan your backup exists on the PC of someone you know (and vice versa; you can back up your mom at your house and set her machine to back up on yours). Since the Crashplan company doesn't have to pay for either storage or bandwidth, it can offer a lower-cost service: a $50 one-time license sets you up; most online backup services charge a monthly fee. Since our previous coverage, CrashPlan has added new features like Web access to your files, business accounts, and a "seeded backup" option: you do your first backup on a spare drive on your local machine, then install the drive on a friend's computer across town, after which only file additions and changes need to be transmitted.

Gomez. Unlike the previous two products, which employ your unused hard disk capacity, Gomez pays you for borrowing your bandwidth. The company evaluates response times and performance of major Web sites, which are its clients, using real-world computers on real consumer Internet connections. To do this, it installs software on end users' machines, and when these users are not using their PCs, the software on them hits the test servers and reports on the speed of access. Users don't get to see the data, and Gomez has no access to users' traffic (or so the company says). The big benefit: Cash. The testing happens when you're not using your PC--like when you're asleep--and you get paid for the bandwidth rental. Company spokespeople say most people make only a few bucks a month but some earn up to $45 a month from the service. Could be a good way to repay yourself for your Internet connection. (I'm going to see if it will work on my always-on Windows Home Server.) Note that if the Gomez network already has enough users in your area, your PC might not get much test work, and you won't make a lot of money.

From the save-the-planet perspective, I'm not sure it makes good sense to leave a computer on just so you can use services like these that use up your idle resources. But if you have computers you're going to leave on anyway, your math may show that it is more cost-effective to pay the added electricity bill in exchange for a lower cost of online storage, or income from the test service.