These are exactly the technologies that I find so exciting. They are also what brought me to Steemit. IPFS looks very promising and I'll be experimenting with it and hope to share what I learn.
Buying and selling is the "killer app" to me, although video sharing might be a close second (as the sharing of information in a personal way has a lot of power). I'm very excited about OpenBazaar, a decentralized way to buy and sell using crypto-currencies. In version 2, OpenBazaar will use IPFS to store the listings so that they will stay online even if the person's computer who posted the listing goes offline. Very exciting times!