Learning the ins an douts

Hi. My question relates to web programming (specifically, developing web apps). I am a programmer with experience in PHP/MySQL, etc, but I do not consider myself experienced. I can hack together things easily, but I have not taken courses such as operating systems/compilers/etc. I wanted to post this for myself and others who have not completed or started a CS degree. Are there any books out there that touch on these subjects but are geared towards the trials and tribulations of a web application developers? I have started reading a lot of O'Reilly books on web application developnent, but I wanted to ask specifically if any one knew of books that covered these CS topics (or if those CS topics are even important when prototyping/hacking/building). I also wanted to share a resource I found. Safaribooks.com is a website for reading web development books online, where you pay $22/month and they give you unlimited access to O'Reilly books (and a lot of other web developing books). I wanted to purchase many different books as references, such as books on front-end, web scaling, css, etc, and found it impractical, but this site turned out being very useful. They have a 7 day trial for those on a ramen budget, perhaps wise to use it when necessary! I found this site useful, and thought it might be useful to other startup hackers as well. Thanks :)