Ways to start a program at windows startup?

Question

I had an updater program that started itself on logon but was not able to find it anywhere. After some time I found a hidden task in the task scheduler and managed to turn it off. That made me wonder, what are the possible ways to set a program to run at startup? I know of:

1. Registry CurrentVersion\Run (msconfig Startup tab)
2. Startup folder in the start menu for current and all users.
3. as a service
4. via task scheduler
5. as a driver?

After some searching I also found https://stackoverflow.com/questions/3070152/

Are there any other ways? Or other folders like the Startup folder which are executed at startup?