Reddit's subreddits are really a nice place to be. Not the funny/wtf/vidoes/politics etc, which will overwhelm you quite fast. There are some really useful subreddit which are of good quality, but because of their smaller sizes, are difficult to know about.

I feel these subreddits are worth a try: compsci (http://www.reddit.com/r/compsci) explainlikeiamfive (http://www.reddit.com/r/explainlikeimfive/) programming (http://www.reddit.com/r/programming) (There are a links to other subreddits of similar type in the sidebars of these reddits, which can be further explored).

One caveat is that lots of articles/links/posts from those places turn up here at HN as well. So there is factor of duplicates involved.

All any of your interests might have its own subreddit. If it exists and there isn't too much trash, those can be looked at.