Ask HN: Apps to document my life?

I'm a data junkie. I like measuring stuff and analyzing it, but I've usually used paper/pen, or the odd text file here and there. I also recently got myself an iPhone 4, and it seems like a good device. I'm looking for suggestions on which app(s) to download so that I can log daily details about my life, and analyze them later (a data dump would be good) I'd soon like to be able to generate reports in the style of Nicholas Felton (http://feltron.com/); I don't even need them to be pretty, I'd just really like to see key areas and see how I can become a less stressed, more productive person. Any suggestions/tips? Do any of you do stuff like this?