Most of the HN crowd probably already knows about most stuff I read, considering y'all introduce me to so much of it. Nothing really jumps out aside from those sites. Besides, at the end of the day I actually have to do stuff rather than just reading and commenting about it. :)

Oh, one thing: Slideshare. If you get interested in any sort of technical topic, and you don't have infinite budget to attend conferences where people drop their secrets about it, go to Slideshare and view the slides instead. I've learned so much there is is incredible: everything the YSlow guys have said about front-end performance is solid gold, the recent Startup Lessons Learned conference was a veritable bonanza of good information (expect me to steal more ideas from it), etc etc etc.

Plus, if you are particularly interested in A/B testing case studies, we have A/B IdeaFox: a search engine for case studies - http://visualwebsiteoptimizer.com/ideafox.php