You can take any mod that only uses a control.lua or files called from it (any mod that doesn't add new entities/items/technologies) and put the contents into the savegame's control.lua.
I've used this to provide a player color gui on my servers without requiring the clients to install any mods ...

Hi everyone! I really love Factorio and I have already played around with making my own little mods.

What I need now is some kind of way to get data from my server like, how many players are connected. For this I would need Factorio to write it's server status to a file or send it to a server, or ...