YellowPin

Pin's starting their assault on social networks with a Facebook app that lets you alert signed-up friends as to your exact whereabouts and activities by texting 'Pin, which'll then post where you're at; you can also text 'Pin to get whereabouts texted back to you on other 'Pin users who you're friends with on Facebook, and when that text returns nothing, you'll remember why you had to turn to the Internet for friendship in the first place.