Q:

How to utilize the free time during office hours?

I am a software developer and most of the times when I find free time I read few news or technical websites like Techcrunch, Gizmodo, etc or read Twitter. How do I utilize this time to the maximum, instead of wasting on browsing unnecessary things so that it will help me grow professionally?

A:

What I do is identify a technology that I'm interested in and then research it in my brief (and rare) moments of free time.  For instance, there may be a new technology or framework that I've been hearing about and I think it'll become useful to me in the future.  What I do is get a book (an ebook usually) and then read up on it. 
For me, a key is to stick with one subject until I'm ready to move on. I'm rather ADD and keeping things to a single subject helps me maximize the time I spend as well as my typically limited attention span.
I try to keep the subject matter limited to technologies that I can pick up and put down at a moment's notice without having to get myself into a mode of deep thought.  For example, some hot new javascript framework versus quantum physics.  :)
I do try to keep my searching for new topics off of work machines because I don't want to be perceived as "that guy" who is always browsing, even if the searching is technology related and worthy of my time.

