If you're not parinoid, your eyes aren't open. While the "cloud" makes lilfe incredibly convenient, at it's core, you shouldn't trust it. The price you pay for doing everything in the cloud is your privacy and the trust you give to those companies not to loose your data. While google or amazon is incredibly unlikely to crash and loose your data, I feel safer having it backed up at home.

Because I am a healthy skeptic and because I want control, I decided to build my own home server based in Linux. Some of these things are useful for anyone that uses computers these days, other items are especially geared towards nerds like me. I've started these things up in order of importance.

1. VPN- A Virtual Private Network allows you to create a secure connection to your home network from anywhere in the world. All of your traffic travels encrypted to your network and then out to the interenet. A VPN allows you to connect securely to home. 
2. File Server- A Samba file server allows you to share files between Windows computers. I think Mac's can access them too, but who cares?
3. Webserver- There are many options, but an Apache Web Server allows you to serve websites to web browsers. A webserver is what most people think about when they hear "server."
4. Certificate Authority- As your server grows, you will eventually want to access it from the outside world. You may want to buy a signed certificate from a certificate authority, but since this is all about not trusting anyone, you may want to make your own. Certificates allow you to authenticate identities across the internet.  You can use these to secure your VPN and your webserver.
5. FTP Server- Allow access to your files across the internet. 
6. GIT Server- GIT is a version control system for writing software. If you're a nerd, you may not want to post your code all over the internet, but you still may want to collaborate on some projects. GitLab provides a GIT server and web interface to meet this need.
7. openHAB- Home Automation software belongs in the home, not the cloud. I installed this system to manage my growing number of connected devices without having them call out to the cloud every time I need to switch a light.