Idea Banks: 'oh yeah' moments

How do you collate your ideas? They come out of no where at random times of the day and night so having a clean way of harvesting and collecting them is vital.

I just use the iPhones notes and I just email myself updated copies once a week. 

You have Idea Banks for all your clients, projects, whatever. The ideas may not be right for now but in time you will know when to mention them to people who can help execute them.

It's important to collect your Ideas and save them, never delete them. Go through and read all your Idea Banks once a month to refresh yourself. Thats when you get those "oh yeah" moments, they make you think, take ideas in different directions and flesh out ones that could be useful right now. 

How do you collect up your ideas? Do you have an Ideas Bank?