Neat application - keep up the good work. A couple points of improvement are 1) after being redirected to the site, I couldn't really go back to where I came from (HN, in this case), 2) not to be overtly meticulous but I was wondering why the buttons are pushed around 2px down on hover (tested in Firefox 4 on OSX 10.6), and 3) the comfy AJAX-y feel could be there if the box was a static size beforehand, when latency increases client side, the kill/keep buttons are really in a funny position. Overall this is definitely something to use again - cleaning up lists on Twitter seems to be egregious (and I'd imagine without the API rate limiting it'd be more than 1 person/screen :-P).