SMS and Gmail notification volume Is there an app that can control the volume of notifications for separate apps like SMS and Gmail? I searched around and found a number of old threads that says it's not possible.  There was an app called WhoIsIt that did what I was looking for but it seems to have been discontinued.

Otherwise I guess I'll have to make a custom ringtone that's louder than normal and use different ringtones for SMS and Gmail.

I'm on Android 2.3 btw.
Quick Answer
Volume control is managed system wide. The Android OS doesn't support independent control per application, only per stream type.

Technical
The AudioManager Class only provides developers a way to adjust the audio volume per Stream type, not per application running.
This means that when setting the volume for a specific stream, will affect the entire system.
Currently available streams:

STREAM_ALARM - The audio stream for alarms.
STREAM_DTMF - The audio stream for DTMF Tones.
STREAM_MUSIC - The audio stream for music playback.
STREAM_NOTIFICATION - The audio stream for notifications.
STREAM_RING - The audio stream for the phone ring.
STREAM_SYSTEM - The audio stream for system sounds.
STREAM_VOICE_CALL - The audio stream for phone calls.

Most of this screams exists since the API level 1, and continue to act the same way on the current API level 16.