⌘⇧D sends mail in the MobileMe mail web app just as it does in Mail.app in Mac OS.

Like the unofficial Gmail bookmarklets, you can now bookmark the ‘compose new message’ window of MobileMe Mail. As long as you’re logged in, visiting the link above will create a new composition window with all the contact auto-complete and rich text editing tools you need.

Strangely, while sending a message from this window seems to work, the window does not appear to display proper feedback. Clicking the send button will display a typical Mac OS X “spinner” progress UI and a “Sending…” message, and even though sending works, that progress UI never changes. Hopefully, the MobileMe team can fix this UI quirk and keep this convenient way to send messages.

If you mis-enter credentials in the login form at Apple’s MobileMe site, it will shake and wipe out the incorrect password to help reinforce the fact that you goofed up - just like the login form on a Mac.