Custom Fit Earphones

Canalphones, in-ear monitors IEM

All Orchestral Players Should Wear Ear Plugs
Elacin ER
Musicians' Clinics Temporary Hearing Loss Test App $$

Sensaphonics
Sensaphonics custom sleeves for Shure SCL Series SCL3, SCL4, SCL5, SE series SE210 SE310 SE420 SE530
Etytomic ER-4, ER-6, ER-6i

Ultimate Ears
Westone (some made by Shure?)
Future Sonics
Future Sonics SofterWear for Sennheiser IE4, XtremeMac FS1 (made by Future Sonics?)
Etymotic Research Musicians Earplugs fit ER6 with er6-15 adapter

TMO Buyer's Guide - In-Ear Headphones Compared, Low-End to High-End || The Mac Observer
iPO's Buyer's Guide - In-Ear Headphones Part I: Universal Fits
Buyer's Guide - In-Ear Headphones Part II: Custom Fits