Generally speaking I just keep an eye on my twitter feed because I'm usually pretty busy.

On a day off, in addition to HN I'll occasionally check the following:

http://forums.somethingawful.com/forumdisplay.php?forumid=22

http://slashdot.org

http://boards.4chan.org/g/catalog

https://news.layervault.com

https://lobste.rs

http://techcrunch.com

http://www.technologyreview.com

but most of those are crap.