First post here. New to Wp & I've been learning much from y'all... thought I'd toss my 2 cents in for starters.
In currently working with the K2 theme I was stumped on how to get the header image (optional) to produce a link. What I did was the following & it seems to work.
In header.php, line 48, change the line
<div id="header" role="banner">
<div id="header" role="banner" onclick="location.href='http://www.mydomain.com/';" style="cursor: pointer;">
I found this code snip in http://codex.wordpress.org/Designing_Headers which made perfect sense. I was working late when I did this on a site I was tweaking so I haven't tested it thoroughly yet. It seems like the cleanest way to achieve the desired outcome. Please post if you have success with this or have a better method.