Here's an Outlook Web Access (OWA) feature that's in some ways little known. Although if you search for it, you can find articles talking about it. It's the ability to drag and drop attachments on to a message. What makes this possible is our S/MIME control.
Try it out. Install the S/MIME control from the Options page and then bring up a new mail message. Now select a couple files, drag them over and drop them on to the body of the message. They get added to the attachments list just like that. It's so much better than having to post each individual file attachment which is typical of a web app, don't you think?
Looking for more OWA tips, check out KC's blog on Exchange and Outlook.