One weird idea I long for is a kind of lifetracking application, that just automatically journals your activities for you. So you can look back and see, today I went here, here and here (and these are the photos), and I read these emails and I spoke to these people for this long and spent X hours sitting at my desk and this long commuting. The more data you can grab from different services or other iPhone apps - twitter, money tracking, whatever - the better picture you have of what you did in a day.

When you have that data in a grokkable form, you could do some really awesome analysis of what the hell you're doing with your life. ;)