Bright Kite
I have been trying out Bright Kite for a while now. If it were not for the fact that it has some issues with Verizon (Verizon causing the problems apparently), I might be using it more. It is a little bit like a location-based Twitter. You can set it through SMS, e-mail or web-based interface to set your location at various degrees of resolution depending on the level of relationship (Friend, Anyone, etc.)
I think it is really best to be used in a fairly populated area or at a conference-type of environment. By posting location you can see who else might be or was at your location. However, it is useful to see where people you know might be, particularly if you want to get in touch. For example, if a person you are tracking is in London as opposed to San Francisco.
There is a sense by some that this is “stalker-ware” but I think this is only the case in general. You are the one that sets the position, and if you are even going to bother to set your location. Like Twitter, it is essentially a micro-blogging platform with location added in — Bright Kite pushes the idea of setting location without a GPS. While I would not like to “stalk” my friends it is a good way to get a sense of where they are if I want to get in touch.
I have a few invites if anyone would like one.