EarJellies ear plugs (were) available through a crowd-funding campaign on Kickstarter:
EarJellies use MemorySil’s shape-memory. They are molded to have bulbous ends, but you can teach them to be long and thin by rolling them out between your fingers. They’ll remember that new shape long enough for you to insert them in your ears, then gradually return toward their bulbous shapes. When they encounter your ear canal, they seal it gently and stop changing shape. The result is a perfect seal and extremely little pressure on your ear canal.