Ask HN: I have too many ideas! How can I get rid of them?

I have a problem; I have too many ideas all the time, and they bother me. They are popping back in my mind all the time and I can't escape from them. Whatever project I start, whatever new field or area I look into, I usually have a ton of new ideas instantly; how could I make this better, what would be killer features, how could the UI improved, etc.. Tons of them. Right now I have more than 40 project ideas and 546 new issues (mostly feature ideas) in my private tracker which I would like to implement (LOL).

Writing them down as David Allen suggests in GTD helped a TON, really. Once I write them down, they don't come back as much, because I know they are in a good place and won't get lost but still, if I don't jot down an idea immediately as it pops into my mind, it just doesn't let me do my job...

Another good practice is to try to focus on one thing and one thing only and do only that and don't bother anything else. (e.g. one project at a time)

I read a couple of articles in the topic but I still have this problem from time to time, and sometimes, I just can't focus on what I need to do right now, because of them.

If you suffered from this, how did you overcome by it? What techniques could you stop them popping into your mind? How could you forget or not deal with them and increase your focus on what needs to be done instead of daydreaming?