You may remember a while ago I introduced the site DonateBot.com here. It's mission is simple: By just opening this site on your browser, it would automatically activate your Java application to start "donating" your unused potential CPU processing power to the networks that require much processing power to conduct their research projects that may ultimately benefit the society as a whole. Such application is called "distributed computing." Through my short time of using the site, I found nothing detrimental to my everyday computing and even to my computer, except that the computer may get a little more heated because of the increase usage of CPU. I have also had several contacts with the site's owner, Tom Bak, to ask him some questions about the site. He seems very responsive to my questions and is dedicated to make the site more informative to the users. I have trust in him.
Meanwhile, there are several more established sites out there that are promoting distributed computing for various research: from fighting AIDS to predicting future climate change. Most of these sites require you to download a special software before you can join the distributed computing networks and start "donating" your idle CPU power to these networks. I haven't tried them yet but you can give them a try and share your experience with me.
