What is a Pastebin?
A pastebin or text storage site[1][2][3] is a type of online content hosting service where users can store plain text, e.g. to source code snippets for code review via Internet Relay Chat (IRC). The first pastebin was the eponymous pastebin.com. Other sites with the same functionality have appeared, and several open-source pastebin scripts are available. Pastebins may allow commenting where readers can post feedback directly on the page. GitHub Gists are a type of pastebin with version control. - see related wikipedia page
A decentralized pastebin appliacation on STEEM

Is it possible? First thoughts:
- Storing unrelated, out of context data as steem posts are inefficient.
- You cannot post more than once in 5 minutes.
- Most of the data you push to Pastebin websites are not worth rewarding.
Steemit, Busy shouldn't show that information to your followers. So, what to do?
custom_json
STEEM blockchain allows any type of JSON data into blockchain with a custom_json operation. See this post for an example.
A simple data structure with custom_json to store text data:
{
required_auths: [],
required_posting_auths: [<account>],
id: "paste",
json: [
<add>,
{
title: "title of the paste",
body: "the text"
tags: ["a", "b", "c"]
}
]
}
This would do the job. Plus, no garbage content on interfaces like Steemit or Busy. A simple form with these inputs -on a web page- can broadcast this into blockchain.
However, how can we browse them?
indexer (backend)
Our custom operation is not a part of blockchain consensus, we need an indexer.
A background process should listen to all custom_json operations signed with the paste id and store them in a separate database. (MongoDB?)
Then we can query any item by accounts, tags, or search text with the title.
Eg: "Fetch the entries including 'python'". A simple REST HTTP API can expose MongoDB queries.
api/v1/latest
Return latest entries.
api/v1//bin
Return entries related to account.
api/v1/search/title/<text>
Search entries including <text> on title field.
api/v1/search/tag/<tag>
Search entries having <tag> on tags field.
I will probably implement a simple decentralized Pastebin app with that design, in my free time. Thoughts?