So, Getting people to sign up to your nameless site is a little difficult if you're not a huge network with lots of players. However, I had an idea to bring more life and reason to sign up to server owners websites.
The concept is, You log in, and every day you log in, you get a token or point 'you can call the currency whatever you want'
And there is a page called 'redeem' and a module called 'redeem' the players can use the points they collect over time to redeem some preset items that you define, It would most likely need to be connected to a minecraft plugin also but I feel like this would be a really cool premium resource that I and a few I know would definitly pay for.
Theres also some concepts you could play around with, Maybe theres a whole list of items you put in a list and the 'redeem' button actuallly says 'spin' wheel, and it spins a wheel and gives them a randomly selected item from the list based on odds.
I know it's unlikely somebody would develop something this complex. But I really feel like it would be an awesome feature. Also the ability to choose which server you want to redeem the item on would be nice for us with big network
'Congrats, You won 64 diamond!'
Where would you like to redeem it, - Survival,Skyblock Etc