My site is called "Human Performance and Achievement Resources" because the general idea is to provide, well, resources. Links to websites with great content are some of the best resources I know.
Of course I recommend my own site as a source of information on productivity and performance. But there are a number of top notch sites that also cover the major issues affecting productivity. I think you'd profit from reading them regularly. Here are my current top 10 picks.
• Lifehacker -- http://lifehacker.com/. If you don't know about this outstanding daily blog on personal productivity, then you've been living in a closet without an internet connection. It's all about working smarter and more easily. About saving time. About sites, software and other tools that help you do that. It's the best of the best.
• Stepcase Lifehack -- http://www.lifehack.org/. I could almost write the same description as I did for Lifehacker. So, ditto. Learn tips and tricks. Get organized. Get automated. Hack your life like you'd hack your computer.
• Zen Habits -- http://zenhabits.net/. Simplify. Organize. Stop and breathe. You have plenty of time to get done what needs to be done. You just need the right perspective. Change your thinking, change your life.
• Steve Pavlina -- http://www.stevepavlina.com/. Learn to be more productive by setting goals and acting with purpose. Live consciously and get things done more efficiently.
• Productivity 501 -- http://www.productivity501.com/. Another tips, tricks and techniques blog. But a different perspective and approach from Lifehack and Lifehacker. Has plenty of "here's how, now go do it," but more "here's how to think about it" than the other two.
• 43 Folders -- http://www.43folders.com/. An irreverent guide to beating your attentional deficits, trying to stay organized and on track, and getting back to work to get the important things done.
• Dumb Little Man -- http://www.dumblittleman.com/. Set goals, simplify, organize, automate, work with gusto. Think about it all in interesting and provocative ways.
• LifeDev -- http://lifedev.net/ -- Helps the "creative" person be about the business of creating. Getting things finished. Distinguishing between "doable" ideas and nonstarters. Having a system and using the tools of creativity.
• Productivity Cafe -- http://www.productivitycafe.com/. Go from overwhelmed to organized, systematized and relaxed. Stop stressing and start clarifying and simplifying. If Zen Habits is too Zen for you, try this thinking approach. Relaxed and fun productivity is healthy productivity.
• Pick The Brain -- http://www.pickthebrain.com/blog/. More general self-improvement than the others on this list. But easy to see the relevance of self-improvement and motivation issues to productivity.
You'll probably think "Where is the link for David Allen's site? 'Getting Things Done' is pretty famous." This list is about websites (or blogs) where I find the most helpful information on productivity and performance. In relation to that, I'd list David Allen's book rather than his site. Sure, he has some free articles on his site. But that's not what his site is for. The book is where the information is.