Here is a list of things I've done that seems to increase battery life on the Samsung Galaxy S Vibrant.
In my opinion the phone has great battery life. However, if you are making the switch from something like a BB Bold 9700, then yes the battery life will shock you a little.
Most people on here who report horrible battery life probably just baught their phone and are using it like crazy. First day I had my phone, I used it non stop, browser, Avatar, Live Wallpapers, GPS, Bluetooth, Wifi...the works. This is not typical, so as you get over the "wow my new phone" phase...here are some things to do to increase battery life. I am just posting ideas that I learned from reading around, self trial, and blogs.
Okay:
Live Wallpapers Turn Them Off. Drains like Crazy.
Wallpapers with Bright colors Off. Instead..take a picture with your finger over the camera, this will take a pitch black photo, set this pitch black photo as your wallpaper. Super Amoled uses less battery to display black. It also looks really cool with a black background. (Read that on this forum I think, who ever originally posted this idea thank you, it seems to decrease the screen usuage on the battery indicator).
Doing the above steps, has taken my display usage down to 20 percent. It was previously at 68 percent battery usage. To install the battery use app. Go to an available home screen, press the screen, hold it down for a few seconds, then click on shortcuts, then scroll down to settings, then click on battery use. This puts the app icon conveniently on one of your 7 home screens. Now click it, and it shows what the battery is using most of its energy on.
Turn off all non-important syncs such as weather, news, only required ones. For example I only run GMail sync. When I want the weather or news update, I just do a 1 time sync refresh.
Bluetooth off unless needed
Wifi Off unless needed
GPS off. Some say GPS doesn't use battery, unless it is actively being used. I don't know, I just leave it off, unless I'm using navigation.
Haptic Feedback off
Brightness set to minimum... helps a lot!
There is a second Brightness setting for the stock browser...set that to minimum also. Go into your browser, then brightness settings.
Random noises, system sounds, vibrations, keypad click sounds, all of that off.
Set your display to turn off quickly, for example 15 seconds instead of 1 minute.
Let your battery drain almost fully a few times, and do a full charge before unplugging. This appears to help me keep a full charge.
When on the go, minimize streaming video, pandora, music players, avatar, etc. Common sense but some people don't realize some things use more battery than other things.
This last one is optional, no proof it really works. Install Advanced Task Killer and kill tasks all day.
Other common sense stuff. Have a car charger with you. If you have a laptop at work or school, carry the usb charger, plug it into your computer and charge on the go. Buy extra batteries. Purchase a portable charging unit. It is a device that stores charge portabily, then you plug it into your phone, and it transfers the charge to your phones battery.
If you have any more suggestions, add them to the list.
Personally I think, leaving everything running still gives me great battery life on this phone. As long as you get over your initial few days of massive use, the battery should be fine with everything turned on. If you want super battery life, do the steps above, it helps.