Managing creative ideas

I decided to start a 'random ideas' book to help me stay focused on the tasks at hand. Most of the time, midstream through a project, I will have a sudden burst of inspiration about a new project. Since I love to begin new projects, old goals have a way of being neglected. Just having a book to put my ideas 'on hold' allows me to stay focused on current projects, without losing the new creative idea.

Does anyone else having a system of managing new ideas or projects so that they don't interfere with current ones?