I think both the beeminder blog itself as well as the complice blog feature good starting points for what I’d call second (or third?) wave productivity, which includes a lot of hints and links, etc. vis-a-vis quantified self and behavioral economics.
Very important, as it informs a lot of discussions around productivity still is the getting things done system by David Allen. There are a lot of tools who work with this methodology in mind. If you want to see early stuff as regards to personal productivity on the internet, 43folders still is a helpful resource, even though many tools and some approaches are obsolete. Merlin Mann’s approach still is a very good example that constant reframing of the akrasia problem is very helpful. A good introduction to what has been called time boxing is the pomodoro technique.
Note taking is an important skill. Looking into the theories and practices behind successful note takers is important. A good blog for that might be Taking note. I’d suggest really looking into Niklas Luhmann’s Zettelkasten System as it starts to be creative for you at some point of entering notes into it.
Also, Peter Drucker’s work is very important, historically speaking.