for the moment i'm using it just for gambling because whit bitcoin you don't need to do verification like on fiat online casino
i also use bitcoin majority for gambling, i also have some stored in a secure way to gain something in the future.
Gambling with bitcoin is good as it make me anonymous,for me i have bitcoin just to gamble it at casino.
i think that for the moment the killer-application for bitcoin are just 3: gambling, porn, and darkweb