Why do you need Virtual Appliances?
I'm interesting in virtualization idea, especially Virtual Appliances proposed by VMWare. Why? I'm too lazy to install some softwares myself. I can but I don't want to waste my time. It would be extremely easy by just downloading virtual machine image, turning it on, customizing a bit, and it rocks in a right way.
If you can't imagine the advantage of virtual appliance, you might think about developing a J2EE application. What do you need to have? Exactly, I don't know too. There are so many Java tools and libraries. At least, I know Eclipse. But problem is not that simple. Eclipse is very modular. Most features are divided into independent plugins. I don't know about that again. In order to develop web application, I do need something like Tomcat, Struts, Spring, and lots more. It would be easier to create a virtual machine image which provides all of these preconfigured and ready to use instantly. Another example is to run applications on completely separated environment. Assuming I would like to download e-mail from Yahoo! into Microsoft Outlook Express. Unfortunately, I don't have premium account so I have to use third party tools like FetchYahoo or yahoo2mbox. This kind of tools are written in Perl. It is possible to run Perl on Windows platform but it might mess up my system easily because I must have POP3 server installed to help Outlook retrieve mails in mbox format. It would be better to run FetchYaoo and POP3 server on other linux box. Anyway, I would like to fetch mails whereever I am so it should be the same machine. Virtualization could help me slove this problem by running the linux box only when I want to fetch mails from Yahoo!. However, setting these things might not be so easy for newbies. Virtual appliance simplifies all steps into just download and run.