Robin Nixon
I am the author of several books on computing and a number of publications for companies such as the UK's Channel 4 TV and the Department of Trade and Industry (now called the Department for Business). My first book (in 1993) was "The PC Companion", which fortunately sold very well, and a reduced version of the book was also given away free on the cover of 35,000 copies of a popular UK computing magazine. In 2009 I wrote my most successful book to date, the best selling title Learning "PHP, MySQL & JavaScript". I am the author of the Plug-in series of programming books: "Plug-in PHP", "Plug-in JavaScript" and "Plug-in CSS", and also wrote "HTML5 for iOS and Android", a book that shows how to make professional web sites and downloadable apps for Apple and Google mobile devices and phones. In a new departure I have just completed "Creative Visualization For Dummies", the first in a series of motivational and inspirational books. The next is "Yes, I Can!" which has already been published as a popular free teaser on Android and iPhones. I will publish the full version under the new Nixon Publishing brand.
On Five Writers Explain How They Got, Kept and Fired Agents
As a published author of ten non-fiction titles I gave up on looking for agents a long time ago. None of my books were sold through an agent, instead I used research and hard work to find just the right editor at the right publishing house for each book (so far O'Reilly, McGraw-Hill and Wiley). Even though some of them say they only accept agented submissions that's not always the case; if you can find a way to establish a discussion with an editor you may be able to pitch a book.
The last time I tried to get an agent was after I had seven books published, and even with that track record it was nothing but dozens of rejections (well mostly being ignored actually). So I went back to editors I knew and asked if they knew other editors suitable for my book, and one of them did, which led to a commission.
Since then I only ever deal with editors and have been able to negotiate acceptable terms for my books that I doubt an agent could better anyway. I'm not sure how it works in fiction, but for non-fiction, I am proof that you don't need an agent (and now I'm not sure what I'd do with one if I had one :)