This article states that you can compress files on client-side memory using Silverlight:
[login to view URL]
What we need, via ASPX or HTML page using classes described on the article, is to select one or more files on the client, compress them on client-side memory and upload the compressed file to a remote server.
We have [login to view URL] program, which is working. It uploads whatever is on memory stream on client-side. You can call it for uploading the compressed file.
For selecting multiple files on client has to use some control like File Open Dialog control.
I'm open to fair suggestions.