I always have colleagues seeking advice about where to get earplugs, how to find a good audiologist, and other good questions, so here are some resources on hearing health for musicians:
Atlanta Hearing Doctor: Classical Musicians and Hearing Loss
Acoustical Society of America: Sound Exposures and Hearing Thresholds (a research study from 1999)
Incidence and relative risk of hearing disorders in professional musicians (a research study from Germany)
Music Exposure and Hearing Disorders: An Overview (research article)
BBC Guide to Musician Hearing Loss: A very neat article looking at different venues in England, the size of stage, reverb, risers, etc.
Pitch Discrimination while wearing Musician Earplugs: This is a fascinating study that can help clarify how much one can really hear while wearing earplugs.
Westone Musician Earplugs: these are the custom earplugs that I currently use, and you can get them at an audiologist near you
Etymotic earplugs: less customized, but still great and way more affordable
Wenger Acoustic Shields: for ensemble use
decibel 10: decibel reader app for iPhone
Sound Meter: decibel reader app for android devices
If you have more suggestions for products, studies, or more, let me know and I'll add it to the list!