I put this in the Feedback and then thought I'd put it here, too.
I think it'd be very helpful if you had a search box up in the header, or at the top of the page every page. I see it on many pages. The place I missed it the most was on the homepage. I came to the network the other day wondering if someone had written anything about a specific topic and since search wasn't on the home page I kind of had to search around for it - haha.
If you don't like the idea of having it on every page, at least adding it to the homepage would be great.