I've read a bunch of these 'become a better dev' musings and I like this one the best. Most of the posts I've seen (other than this and Hanselman's) seem to assume that burying one's nose in books will bring about some sort of magical transformation.
I have yet to see anyone mention eating one's own 'dog food' though. Not that I do it much, but going on a strict diet of daily steaming lumps of your own dog food seems important. Humility and the ability to prevent defensive posturing when interacting with users are essential traits for a 'good' developer. Eating yr doggy food can help bring that about.
These are very good suggestions. Just thinking about code, and just one language, does not open up your mind. I remember when Dave Thomas (Agile Developer, not burgers) gave a keynote on software development and he went through a series of paintings and then got into how they were created and how the masters created their masterpieces. The thing that most of us did not realize is that the great painters threw away a lot of their work because it was not good enough. He also explained that sometimes they would draw, with pencil, on the canvas to get the shaping just right before they started adding paint. It is sort of like prototyping and since it is much easier to move a line drawn in pencil it helped them create the new paintings more quickly and also get to what they envisioned.