Over the last 15 years I've been trying to move away from relying on 3rd parties for critical services I use. It started out as a way to learn what standards existed and how they worked in practice. It's one thing to intellectually know what's there, but a whole other thing to use what's there in your everyday life.
In 1999 I started with my own web server, rather than relying on a 3rd party host (like Geocities). I bought a decent desktop computer and installed Slackware and Apache httpd. This has been crucial in my career growth as it allowed me to learn new web technologies as they've come out.
In the early 2000's I decided to run my own mail server. I tried out several and finally landed on qmail. It worked well on Slackware and it supports SMTP Auth. I added IMAP support using Courier IMAP. But I've since switched to Dovecot. qmail also supports integration with SpamAssassin for SPAM detection and filtering.
In the mid/late 2000's I heard about a new web based mail client called RoundCube. It supported drag and drop like a native email client and I was hooked because it allowed me to remotely access my email with a feature rich client similar to what I had been using via native clients. In the last several years it's added support for plugins which have brought CardDav and CalDav integration.
In 2007 I built my own RSS aggregator (which I have since open sourced) as a way to learn Ruby on Rails. This has been the single greatest learning tool for me. Every time I want to learn a new language or platform I write a client for my aggregator. Google's decommissioning of it's rss client had zero affect on me :)
About four years ago I decided to move from running my services on a standalone desktop box to running them on a server in my own cloud. The big reason is that I needed a server that I could tinker on that won't affect my email, calendar, contact, and file access. So I built my own server and installed XenServer. This has allowed me spin-up and play while also keeping my critical services running rock solid.
About 3 or 4 years ago I ran across Owncloud. I was looking for an alternative to Dropbox because I wasn't happy with Dropbox's model of having to use their software to access my files. Owncloud was revolutionary in allowing me to stop relying on 3rd party services for access to my critical data. After installing Owncloud I controlled my calendar, contacts, and files.
Sometime in the last 3 years I stumbled across GitLab, an open source alternative to Github. I write a lot of software at home but much of it is very specific to things I want to do and aren't really interesting from an open-source perspective. GitLab allows me to work on private projects and access my source code using a remote git server. When something becomes useful to more than just myself I open source it.