A Silicon Valley startup called offers a free iOS and app called that's designed to gather available phone sensor data and upload it to the company's -based servers.

Instead of using the data it gathers for advertising purposes, Placeme just makes that information available to you -- and nobody else.

Here's by Silicon Valley blogger Robert Scoble with Alohar's founder, CEO and CTO, Sam Liang. (Liang used to work at , where he designed the Google Location API.)

Placeme is what would be if you checked in at every location where you stayed for more than four minutes and annotated those check-ins with other data. Except with Placeme you don't check in. You don't have to do anything. (You can optionally specify or change the name of locations, and add notes.)

Later, you can review a list of all the places you've been, or see them pinned on a . A search button lets you search your history.