人々がそれを返すために画面にメッセージを表示する機能は、Windows Phone 7のように、
I'm looking for an app like Where's My Droid to help locate a lost device.
Ideally I'm hoping there is one that might have two specific features:
The ability to display a message to the screen to help people return it, like Windows Phone 7 will have, as illustrated here.
The ability to turn the GPS on remotely to aid in the physical location of the phone. I do not want to have to keep GPS on all the time, to avoid the battery drain.
Running on a non-rooted Galaxy S Captivate.
Another option: I like Lookout.
In addition to tracking/finding your phone, also does virus scanning and backs up data. It doesn't display a message though.
Try Prey for Android.
Here's a recent review: http://www.downloadsquad.com/2010/10/28/prey-for-android-is-an-open-source-anti-theft-service/
Note that having the GPS enabled doesn't (unlike with Bluetooth) drain the battery. The GPS only uses battery when it's active, which only happens when something is trying to use it.
I don't know of any app that can enable GPS if it's disabled. For the message however your best solution currently is probably WaveSecure.
At least for #2 check out Samsung Dive, if it's supported in your country (it isn't in mine). It should do the trick. Also has remote lock and remote wipe functionality.
EDIT: Just realized that Captivate is a US device, so this is not supported yet (UK and Germany only). Sorry, my brain hasn't completely woken up yet :)
I suggest you get Theft Aware instead. Unlike all the others mentioned this one once installed is totally invisible. You get back to the UI through the call out keypad with a code of your choice. Will send you details on command of whoever has their chip in your phone plus loads of other things. Give it a look, its free. Used in combination with some other security app this is absolutely priceless.
Mobile Defense is great, though in closed beta at the time of posting. It lets you see the current status of your phone, its location (with greater accuracy if within GPS range) and lets you sound an alarm with a message. I am not sure when they will re-open the beta, but I love the product.