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?
swfupload, the best tool I know that lets you do that. Simple, easy to use and even has a fallback mechanism for the 1% web users that don't have flash 8+.
I found that the best way to upload a bunch of files is to zip them and upload a single file (and then decomress it on server). However that's probably not a good option for the audience you are targeting.
http://swfupload.org seems to be popular.
May be interesting to experiment with (EDIT: another) open source flash-based uploader: http://e-mats.org/2008/05/swoooosh-open-source-flash-based-multi-file-uploader/
We had a company come up with a Silverlight upload that could resize the pictures before hand so that the 5MB files didn't have to be uploaded and then resized. The image resizing capability wasn't included with the clr that comes with Silverlight. Occipital came up with their own. You can see it here: http://www.occipital.com/fjcore.html
I don't know what they would charge, but we have been extremely happy with how it works. If you don't need the resize capability before uploading then I would go with one of the flash upload options like http://swfupload.org or http://www.codeproject.com/KB/aspnet/FlashUpload.aspx