An interesting and challenging idea for a web application (doesn't need original)?

Question

ASP.NET

I am learning Asp.net. To consolidate success, I would like to implement a medium / complex and preferably interesting web application. After all, only when you begin to apply knowledge not in abstract examples, but in something more complicated, do you begin to delve into new technologies well. I don't need an original idea.
To be able to apply the n-layers architecture, there was a layer of business logic, a database.
If there are any TK, it will be absolutely fine. In this case, you will need to think about how to implement everything and do it, and not just do what happens.
I hope for your help.
All the best and all the best)

Answer 1

start-ups (not only Russian ones) are published on vc.ru, look there and make analogues or unique ones, which is better For example ,
make an analogue of https://docplus.ru/ for your city work - a personal medical record of the client - some kind of patient care services - analyzes and some business models for planning treatment - telemedicine services (ala synchronization with Telegram and VK bots), yesterday's news https://vc.ru/n /docplus-vk - for any integration with cards, payments, shops, maybe even... ...
I have a couple of my own ideas, but I'm writing them in PHP - I won't share, there the entities are already ready and a lot of things are already ready :) By the way, I'm making an analog from the service written in Asp.net :)

Answer 2

Well, the question :)
Well, I give a hint, now it has become very fashionable to make an online store. Here, do it. Everything you listed will be required :)