The 48 Laws of Power - Robert Greene.
I began reading it with a "know your enemy" frame of mind, similar to why I read some Ayn Rand, hoping that I'd better understand why some people behave certain ways.
As I got further into the book I began reflecting upon the past, becoming consciously aware of all the faux pas I've made over the years.
I started identifying with all the honest, outspoken historical figures that would speak their mind and end up without a head.
I used to pride myself on my
honesty above all else way of life, thinking how virtuous it was to be like Socrates or Galileo. Now I realize that more often than not, I'd just seem like a dick, and probably wouldn't have a head if the guillotine were still in use. Now I put more energy into understanding others points of view, and understand others better as a result. Much of my old behavior was childish.
Others that changed my way of thinking in some way or another:
Rework, Getting Real, and the recent Reconsider post - DHH & Jason Fried:
I'd always considered external funding as the best way to grow things I've built in the past, and wrote off the few bad experiences with this approach as being outliers. After also reading others' bad experiences throughout the year, now I'm wondering if my experiences were perhaps representative of the industry as a whole. Confirmation bias? Maybe. I'm sure there are the rare few good angel/VC's somewhere out there (no doubt someone will reply with "YC"). However, after watching several things I'd passionately built over significant amounts of time be driven to failure by others, I'd much rather bootstrap future projects. I learned a lot from each failure, but trial and error is a shitty way to spend years of your life. Far better to learn what worked from those who succeeded.
Business Adventures - John Brooks:
Until this book, reading about businesses was one of the most boring things I could imagine. Some of it is dated, but there are also many valuable gems that still hold true 50 years later. I now see that with a good storyteller, even seemingly boring subjects can be fascinating.
Freshbooks: Breaking the Time Barrier - McDerment & Cowper:
This tiny book (free from their website) helped me think of new ways to improve my consulting services and emphasize value instead of focusing on hourly rates, which made it easier to make more money.
Various online sales & marketing resources: My viewpoint on the importance of sales & marketing has also completely flipped since the beginning of the year. I used to have the mental image of a used car salesman whenever I heard the word sales, and of Mad Men when I heard marketing. Now I understand that if you don't market what you build, nobody will know that it exists. If you don't experiment with different sales tactics, you'll miss out on a huge amount of users who would otherwise love using your product, but who avoid it because it's priced wrong, or you're unable to convince them of why they'd want to use it.