In the last couple years I've been keeping a semi-daily diary of any activity that's out of the ordinary -- seeing a movie, taking a dance class etc. It's orders of magnitude less quantified than Stephen Wolfram, but it's fascinating to read back through it every now and then.

As I've gotten older, time has sped up. Whole years seem to go by in the blink of an eye and I think, "what did I do in [say] 2007?" Keeping a diary has helped me to slow time town a bit.