I rarely have my Treo set to ring--too loud, obtrusive, etc. But I am missing many calls due to not "hearing" the vibration when the ringer is turned off. Are there any utilities designed to increase the "effect" of the vibration?
Although this will not help you with the vibration strength, freeware Profiles can help with with your volume issues so that you can set more appropriate volumes and tones for work, etc