Write it Out
Putting pen to paper frees your mind for other things.
I am taking a page out of David Allen Getting Things Done system when I say this, but writing things down really is a productivity and motivation booster. Regardless of what it is you should transition it from your mind to the paper to help you really think about it and in turn remember it for the future.
If an idea comes to me for a new venture or project I bring out the trusty legal pad and write a one or two page press release or project profile. I write as if I am writing to explain to others. Expect a stupid audience to force yourself to rationalize and develop all the different aspects.
The other nice part is having a recorded version of the idea, or whatever it is that you wrote down. I am rather forgetful when it comes to new ideas and brainstorms. I keep all of my mental transcripts in a file so I can check back to them later.
Give it a try for yourself and see if keeping track of all your ideas helps you get more done in your daily operation?