Cyanogenmod 7 comes with an app called DSP MANAGER it allows you to boost the speaker and headset volume. Look into locating that app. Google it and go to the xda developer page and see if thats what you need. Also there's info on how to install it
If you are using an mp3 as a ringtone, that can be re-recorded at a higher output level. Not sure if there is an Android audio app that would let you do that directly on the phone, but certainly there are lots of audio apps for Mac and PC that will do the job.
Just wanted to say "THANK YOU , THANK YOU , THANK YOU" . I've been searching quite a while for a way to increase the ringer / notification volume on my LG L39c as the controls on my phone were already maxed out . The DSP MANAGER app works for me ! Thanks Again , Owen Underwood