Well the toaster was designed for notifications, and actually if you go to the 2nd options tab for the toaster you can register mailto: links
(this excludes the 'send as email' kinds of things like in the MS word tool bar)
-I set it to open in the html/basic client because otherwise your loading the advanced client in a new browser window...
For uploading-I'm sure these are already in
bugzilla-though it wouldn't hurt to double check.
But you're probably going to find more requests for a java app window for dragging/uploading documents then you will for a desktop app...
(Though using webdav comes to mind -especially for the briefcase)
In the mean time, Firefox has an extension called dragdropupload that I use for just about any upload dialog:
https://addons.mozilla.org/en-US/firefox/addon/2190
And there's probably something similar out there for IE7 as well.