I already have it on flippa, but I think didn't have a good exposure over there.
Imagine that I start to development the idea about the shorter link website.
I can make a vip users, premium users and free users.
Premium user can select 6 caracters to have shorter link than other site. By example you are a premium user you select from a to e, so your shorter links will be like this: 4btc.co/a if you are a social media manager you will know every letter count. With this shorter link you can use in differents network or url. The script will take the url where you came from and it will redirect to the right link you want to share.
As you can see we can sell a vip membership for 300$ because we only have 36 letter with numbers includes. So with this feature vip user will optain 6 letters, and 50 2 letters links
Vip user will have:
6 links 1 letter + 50 2 letters links 300$
Premium user could purchase the packages:
50 links 2 letters + 100 3 letters - 75$
25 links 2 letters + 50 3 letters - 45$
10 links 2 letters + 20 3 letters - 19$
5 links 2 letters 10 $
Regular users (free) will have a 6 letters links. Ads free. We can ask for donations or we can introduce some ads in the future
If you see we have a great business plan here with this domain, the right person with a little time will gain a lot of money with this idea.
Just with vip user you can make 1800 $. Imagine now you charge all your products in bitcoins (thats the reason why you use 4btc.co) so you will have a very good and productive business
By the way, all links will have stadistical, so you can trace and support your work with that.
Here is the link about the listing in flippa:
https://flippa.com/8732363-4btc-co