There are a lot of free services, documents and other resources out there but it’s often hard to separate the signal from the noise. Here are two links to curated lists of development and security related services.
Software (SaaS, PaaS, IaaS, etc.) and other services for developers that are either free or have a free tier
Troy Hunts list of security and pen testing resources. Many of these are free.
Use getAwesomeness() To retrieve amazing awesomeness from Github
Very comprehensive list of free, computer related books, courses and services.
Free ebooks from O’Reilly
Worlds largest collection of scientific papers.
Free Web Hosting
So, I guess this is a meta-list. That’s ok, I never met a list I didn’t like – so send me details on any other similar lists you may stumble across.