Do you have Minecraft plugin ideas?

Do you have any plugin ideas that I could implement? I currently have no ideas but would like to do something again.

You could perhaps make "Basic" plugins. Something like imitating essentials. You learn a lot and you make a plugin that you can pass on or use yourself.

Can you program? If not, then you should first learn it before you deal with it.

Otherwise:

Start the game and look around. Ask yourself the following questions:

What bothers you? Which things could be improved? What is missing? Which extensions are not yet available? Which existing ones could be improved?

If you have an answer to at least one of the questions, then get involved in the planning and develop!

If you can already program, you can try BungeeCord. But if you want to stay with Bukkit / Spigot, you can do something with MySQL (as an example, a ban system).