I talked how I was wanting to learn Java, so I could start making programs for the Android mobile phone platform.
A project that I thought of, but is perhaps beyond my ability for any time soon, is an application that will tie in with MySpace, Facebook and expendable to other social network websites.
Basically, it searches your friends lists, and if they have an Android phone as well and the location tracking feature turned on, you can see which of your MySpace/Facebook friends are nearby by using the Android’s built in GPS. There are variants I saw of this out there, but none I know tie in directly with the current social network, rather they setup their own networks.
Bes I can figure it, each user who has an Android device, sets up an application on their MySpace/Facebook page that detects when they enable the location feature on their Android. For privacy reasons, all it shows on the webpage itself is that location tracking is on. The back end of the application that the Friends can’t see, but the user can, allows them to block certain friends, or allow only certain friends to see their location.
If two friends have their location tacking enabled, then when they look at the application on their Android, it shows where they are via Google Maps. You can see in an instant if your friends are running late to meet you at the movie theater, or see when a friend arrives in town and a host of other cool features.
At the same time, there are the normal security concerns if some pervert is using a fake MySpace account to find young girls or something like that. I haven’t figured a way around that, but in all honesty I don’t know as if one does need to, since if they already got friended, they are already in, and as I said, the back end allows you to add only select friends to the location tracking, so hopefully that added level of security will be enough. Still the end user license would need to be written in a way so that the developer would assume no responsibility for abuse of the system. Personally, I would add a warning when they add friends to the location tracking that reminds them to be extra careful of whom they allow to track their location (this would be a dialog box that pops up each time, but would probably have a check mark so you could avoid the message next time). By default, it wouldn’t have any friends listed in the allow column.
Anyhow, that is the basics of it. I have more details floating around in my head.
Some of the variations out there currently (well, currently may not be the right word since Android itself isn’t out yet, but these are the ones that I know of in active development) that I know of:

Beetaun. “Social network around geographical content created by people and for people.”
Commandro. Location based social networking utility.
LifeAware.
Those don’t include some of the more game oriented ones which rely on the Android’s built in GPS.