Can somebody make a mail client that works just like TextWrangler so you can have that kind of functionality without all the copy and pasting Barry?

Nice timing! Scott Bynum told me this morning that you can compose mail in TextMate and send it to Mail.app. Turns out TextMate can be made to work as an external editor for Mail in OS X 10.4+ and you can switch quickly between them using key commands.[1] One thing though: it works using an input manager hack, meaning that it uses a process that was intended for one thing to accomplish something else.[2] So this functionality is not supported by Apple and the developer cannot provide the normal assurances.

[1] http://blog.macromates.com/2006/textmate-tricks/
[2] http://macjournals.com/news/inputmanagerhacks.html