There's a whole book on this type of topic called "Making Ideas Happen" that discusses the idea of the "Backlog" for all your ideas. There's also a dedicated website called http://99u.com/ that supports the materials in the book. Check it out.
I should add that I've been using Trello to track my personal "Spark File" (or Backlog) for awhile now. Works wonderfully. And as a bonus makes it easy to "riff" on certain ideas for a couple minutes without committing to anything.
