I use Pomodoro quite regularly. It works really well in most use cases for me - except when I'm deep into writing some code. I can't get myself to stop after 25 minutes - and then I'm suddenly thrown off my schedule and not managing time anymore.
I haven't really experimented with getting my work pomodoro for more than 25 minutes yet - I think that something like a 45 minute pomodoro may help me for the coding sprints.
You can get a lot done in 25 minutes if you turn off all other distractions and also you know that you will be back with them (email, phone, HN, Twitter etc) after a few minutes.
As far as books/timers etc go, I just use a kitchen timer or my phone or a webapp like Tomatoes[1] and I haven't read any books on it other than the wikipedia article.
Here's a variant I used successfully to deal with a complex project that was in danger of ratholing. The concept is "Tabata for work", if you're familiar with the Tabata principles, but it's basically just pomodoro with a twist.
Instead of, say, 20-minutes-on-5-minutes-off-20-minutes-on the same work, the idea is to divvy up a series of tasks and work on each of them for one Tabata sprint. Ten minutes, with five minutes to enjoy yourself between tasks.
Over two hours, you cover eight separate tasks. It's also really surprising what you can get done in ten minutes; send a certain set of emails, review a document, re-work a spreadsheet, test an app. I would not recommend it for coding, for obvious reasons, but if you are in more of a product management role where you are juggling cats and need a structured system to help you deal with all the cats, this definitely worked for me.
It also helped with prioritisation because after spending 10 minutes on each sub-project, it was easy to see what would need more attention that day and have a better idea of how long it would take. The only drawback is that sometimes I really did need a little more than ten minutes (I experimented with some 20 minute blocks, but interruptions became more of an issue).
I think writing (words, code) is orthogonal to time management as a whole. It's task orientated - if you have found a flow or a solution you need to crack it there and then not stop because 25 mins are up.
I can see it working really well for the admin I completely fail to do at work - just 25 mins of focused doing little bits of crap each day would really help - so in fact I might just set aside that time - I will happily down tools halfway through bank reconciliations and it won't break my flow :-)
I use it frequently, and I haven't had to spend a penny on it. http://e.ggtimer.com/pomodoro is good to help. There's very little technique to it, just work 25 mins, break 5 mins, work 25, break 5, etc. As long as you like.
