For Bitcoin to be accepted as a reliable and convenient currency by the average consumer, it needs to become much more open to smaller transactions (such as paying for groceries, bar bills, or school supplies).
Music tracks. Bitcoin should have become the primary method of payment for music tracks. No need for a central authority like iTunes. Indy bands could sell from their own servers and get paid 100% of the revenue. Load up your music player with a few Bitcoins and start listening.
For music track sales to work, transactions under $1 must be cheap and fast. They have to be protected against double-spending, or people will buy tracks from multiple sources simultaneously using the same Bitcoins.
(Someone is
doing this. Unfortunately, most tracks cost 0.01BTC. One costs $0.999 BTC. The cheapest ones are crap techno. None of the music is above garage-band level. To make this work as a business, you need a better catalog than CoinDL.)