WebDev：进行多文件上传的最佳方法是什么？

I want (barely computer literate) people to easily submit a large number of files (pictures) through my web application. Is there a simple, robust, free/cheap, widely used, standard tool/component (Flash or .NET - sorry no java runtime on the browser) that allows a web user to select a folder or a bunch of files on their computer and upload them? I want (barely computer literate) people to eas