Re: sheepworld.de – WordPressMU & Buddypress with custom design
Looks like a nice design, and a great way to show what you can do with buddypress by extending it with some other software. 
I believe you can make a login form outside of wordpress, just direct the action to the wordpress login page. And make the method post. You can even use this to redirect to the page your on right now.
<input type="hidden" name="redirect_to" value="<?php echo $_SERVER['REQUEST_URI']; ?>"/>
