I'm not trying to talk down to you or anything, but why would you want this? I just have a difficult time trying to understand why anyone would want to know where someone else is at all times or why someone would want to let others know where they are at all times.
My father and I are both couriers for the same company. We travel to separate areas of the state, and our call time (The time we have to be at our pickup) is the same. We use tracking apps just so we can hassle each other all night. We know when the other one is at stops and when they aren't, so we don't try calling them while they are in one of their stops. We can pick on each other about who gets done first... things like that. On the more serious side of things, we can also keep tabs on things like breakdowns, which happen frequently when you put on more than 250 miles in one single night. If it happens, I can just pick up the phone and say "I'm broke down". I don't have to give him directions on how to get over to me or anything like that. Or in even more serious events... if he isn't answering his phone, I can check to make sure he wasn't involved in an accident or anything like that.
The other big use I have for it is so my friends can monitor where I am while I am on vacation. (When I go on vacation, I take 2 day - 8 day trips to various parts of the country to go hiking and crap.) I set my updates for once every 10 minutes, so they can look at a map on my website and see roughly where I am. It's just a fun way to share the experience with others. Not to mention the fact that often times I use my tracker to pull GPX files so I can geotag my pictures.
Most tracking apps are not simply "always on", so you aren't tracking people ALL the time. You just turn the trackers on and off when you want to use them. This has nothing to do with spying or jealousy or anything like that... trackers are just REALLY fun (and quite useful) in many situations you may not have thought of yet.
To the OP - I've gone through a lot of apps, and my favorite is "GPS Tracker" by instamapper. It is a free app, but it requires registration on their website. You can set the update interval, and it updates your position to your account on their website. You regulate who can see it through links and turning sharing on or off. There isn't actually an integrated map in the app that you can use... it is all web based. That is the only real downfall. What my father and I do is bookmark the mobile shared page from the other persons phone in our phones browser. Then when I want to check to see where he is, I just open my browser and click the link.
InstaMapper - Free Real-Time GPS Tracking
Google latitude is a complete fail as far as I am concerned. It only updates your position if you are actually using google maps and have it in the foreground. The second it is closed or another app is opened over it, it stops broadcasting your position. Even when it is broadcasting, it only updates every 7-10 minutes. If you want "Real time" tracking (Which google says latitude will do... lol) then this isn't the app for you.
There are also a hand full of other apps in the market which work with text messaging. Again, for me it wasn't an option. I don't want to have to send texts to get a location. Not to mention the fact that half of them don't return it as a position on a map. They just text you with an approximate address.
There are two apps in market which are essentially a lowjack for your phone, but I don't like any app which can be activated by remote. If I want my tracker on, I'll turn it on.
regression said:
The best I have come up with is InstaMapper, but it requires the GPS to be running all the time. This is OK when I'm in the car since I can leave my phone on the car charger, but if it isn't plugged in, the battery would drain pretty quickly.
Actually, not true. You can set the update frequency. Anything over a certain time, and your gps/data goes into sleep mode. It will only come on long enough to update your position, and then it goes right back out again. You set the interval in seconds.
Here are some snippets from their website FAQ.
How frequently do you update my phone's location on the web site?
By default, your phone tries to transmit location data to InstaMapper every 5 seconds if you are moving 20 mph or faster and if someone is currently tracking you online. If you are not moving, the minimum update rate is 60 seconds. If are not being tracked online, the minimum update interval is 30 seconds.
Is my phone being tracked all the time?
Your phone sends tracking data only when our application is running. On the iPhone, the software must stay in the foreground. Other phones allow the software to run in the background.
What information does my phone transmit to InstaMapper?
The data sent to InstaMapper includes location (latitude, longitude, speed, etc.), a timestamp, and a randomly assigned id. We do not transmit your phone number or any other personally identifiable information.
This is how it breaks down...
Line 1: This is where you enter in the key you are assigned when you register your account.
Line 2: This is where you set your update frequency. Anything over (I think) 200 seconds, and your phone goes into sleep when it is not updating. As you can see from the screenshot, my GPS is not active during the picture, but the app is running.
Line 3: No idea. Never screwed with it.
Line 4: Self explanatory.
Line 5: I believe this is the accuracy at which the app will consider itself connected. My average accuracy when I am outside or in a car is usually within 30 feet.
And this is what the other person will see in their browser when they track you.