As an athlete and a coach I have found that many ofthe pre-made plans just aren't personalised enough for those of us who have varied schedules and other committments. Here is one I like:

www.trainingpeaks.com is associated with Ultrafit, by Jow Friel; one of the best known coaches in the country. Through the site you can buy a training plan and then use the site to log miles, training info, as well as utilize the discussion forum. It goes hand in hand with his book the Triathlon Training Bible. Also available are a list of his associate coaches located throughout the US if you want individual coaching or swim lessons, etc.

The program is great because you can download GPS and HR info as well as make changes necessary to your goal races. It defines your plan based on what your weaknesses are ie: muscular endurance etc.