[garysieling]

Reddit and HN (and DZone) can be seeds for other things - e.g. there are a bunch of email newsletters that pull content from there. I've had good luck with some of the programming language based subreddits, because they have a decent size audience but don't always have a lot of content. Usually there are big Google Plus groups of similar size.

Twitter is useful, because you can contact people directly (e.g. people like it when you write something using a tool they built). It's also a good way to connect with people at conferences because there is often a conference hashtag - I met a few people writing up summaries of talks. It seems like a lot of people use it as an RSS substitute as well, so it's a light-weight way for them to follow you.