Name some things that only bitcoin can/should be used to purchase? I've been looking online at peoples experiences with crypto products on Ebay, and I found a thread where the OP was selling mining gear, and sees a lot of disputes/refund requests after two weeks of the gear being received. Obviously the buyers are just mining and looking to return, and Ebay have told him they will side with buyers in these cases..
So, what other things are best purchased with bitcoin due to it's irreversible nature?
All online downloadable digital goods: music, movies, books, games.
The transaction is small and digital, so there shouldn't be much room for disputes and frauds. Downloads are irreversible, too.
E.g.
http://libertymusicstore.net/http://humblebundle.com/Disclaimer: I am the author of the Libery Music Store project above
Apparently credit card fraud is quite common in indie / freemium games - causes problems to small indie game developers. Most likely cardster try out to see if the credit card is working or not.
(Though this answer is more like "things that should be used on sell bitcoin only")