The lovely people at Zoggs have a great resource for swimmers on their webiste swim4fitness.com.
The website is free to register and you can download training sessions at your leisure, from short basic workouts, to triathlon-specific sessions.
The website also enables you to enter some basic targets and monitor your performance as you improve by logging your swimming sessions. You can also enter running and riding times and it will monitor your calorific expenditure for you.
There are also various other links and plenty of information on the site, making it an idea starting point for any swimmer. It is also regionalised, so on the UK site, you get UK information, rather than details on events in Australia...
As the site says: "The Swim4Fitness Programme, by Zoggs, has been developed based on extensive research on how people use the pool. It aims to introduce the principles of interval training and apply them to the water in a simple, structured and accessible way, right from beginner, up to experienced fitness swimmer level. These programmes are designed for the recreational & fitness swimmer, and are written in every day language."
What's more, its totally free - so go and sign up!