Yet another idea... (you're going to get sick of us, Russ!)
Can you put a link in the members profile, so when you click on someone's profile you can just click on the message link and go directly to the 'send message' page, with their username already all in place. From there all you would have to do is type in the subject and the message, and send it off.
The current method is cumbersome at times if you're dealing with a username that is unusual.
A direct link from the profile page to the send message page would really be nice.