The Centre for Effective Altruism in the UK runs a great website called 80000hours.org. I only just signed up a couple of weeks ago on the recommendation of a respected advisor, and so far it looks really great. Sign up for their weekly email series to get it pushed to your inbox in bite-sized chunks. You can also just read the articles and watch the videos on the site. And if you want the content in book form, they have that too (it's only $4 for the eBook).