Uploading Files to IIS Website using Internet Explorer

Hi all,
Is there any way to configure a website to allow an authenticated user to
upload files to it using a browser and HTTP?

Currently we have an FTP site set up to support customers. Our customers
allow us to log into a machine at their site (with RDP or pcAnywhere) and
then use Internet Explorer to connect back to our local FTP Server. We can
then download files to the remote machine and also upload files back to the
FTP site. Note... most sites don't allow us to connect local drives via RDP
and pcAnywhere file transfer is not always an option either.

However, due to security concerns, we are discovering that many network
administrators are locking down FTP (port 21). But they will still allow us
to transfer via HTTP (port 80) in both directions.

Therein lies the problem. I don't know how to configure our IIS Server
Website to accept HTTP uploads... similar to how FTP works. With FTP we can
simply drag and drop (or copy and paste) from Windows Explorer into Internet
Explorer ... either to or from the site.

How can I accomplish the same thing with HTTP?

Is setting up a Sharepoint Server the only option?
Is there a way to configure Frontpage Extentions to accept file uploads to
the server without having Frontpage installed on the remote machine?

Or is there another solution?
Thanks for your patience and help.