Ask HN: Best way to learn the CS background I missed by not going to school?

I'm not sure if this is the right place to ask if it's not I apologize. This is my first post to HN.<p>Background: Basically I've been a developer for almost four years now. I started as a front-end developer writing HTML/CSS/JS, but quickly moved to the back-end writing PHP. Before now I've considered myself a decent developer, but lately I've been feeling burnt out and have been looking to move to a position that would make me happier. I've been looking at Ruby/Rails positions on the various job boards and I really feel like I don't have enough CS knowledge to land any of these positions. I'm feeling more and more like a copy and paste PHP developer. I mean, how can I get a job that is asking for engineers to apply? I really got a punch in the face when I read through a post on Stack Overflow about lesser known data structures like Ropes, and Bloom Filters, and Skip Lists. I have ZERO understanding of this kind of stuff and I think it's going to hold me back in my career.<p>What's the best way to learn all the stuff I missed by not going to school? Are there CS books or technical papers that are pretty much required reading for CS students? Should I take some open courses on the web from places like MIT or Stanford?<p>I can't live my life as a jr. PHP programmer... I'm feeling burnt out as it is, working on the same enterprise app for an employer that won't embrace open source or even new technology!<p>Help me hacker news, you're my only hope.