There are certain parts of the day where we are the most productive. I consider these times of the day for me as being “in the zone”. This time of day occurs around 2-3am, this is when I feel total zen and that I am “at one” with my work. At this time is when all distractions are tuned out and I wont stop until I finish what I am working on. Only my keyboard, 4 or 5
putty windows, and a browser have my full attention.
I’m a firm believer in working in our natural flows and rhythms, aka being in “the zone” or basically just working when you feel like it. When you feel like working or accomplishing a certain task, this is not a forced choice, its something you want to do. And when we do things we want to do, it makes us happy. If you are happy about working, then 1) you are happy about your work, and 2) the end result of your work is of higher quality.
Everyone has their own rythms and times of the day where they are most productive. I strongly encourage you to find yours whatever it may be, at 7am, 2am, or maybe you work best when you are hungry. A happy engineer is a good engineer.

90% of all meetings can usually resolved by just using email or any flavor of IM. I know there are situations where actually having to meet up with everybody face to face is just necessary, but unless I am the organizer or presenter I can be using my time actually being productive. Also in an effort to stay productive through out the day I always attempt to bring my laptop into any meeting, but that can be problematic at times depending on what kind of meeting it is and who is there. (Not everyone appreciates you tapping away at your keyboard and possibly at the same time completely zoned out from everything that is happening.)
Training sessions are probably the biggest hit to productivity usually because of hte length of time. The company I work for basically blocks out a month every year and flys in all the remote and over seas guys to give them training. That is a whole 160 of work time of a mass amount of information that probably only 5% is actually absorbed and the rest is just in one ear and out the other.
With all that said I think its kind of obvious I am a productivity freak, which I am. I take pride in being able to get things done quickly and efficiently without affecting the quality of what I produce. A lot of people are unlike me and enjoy meetings, mainly because it takes them away from their boring old desk and its a change of pace and my argument to that is that is what taking a break is for.