Personnaly, I have built a "self-hosted" stack around the following services:

* Seafile (file hosting/synchronization/sharing/history)

* SoGo (a webmail that work with existing IMAP and SMTP servers and exposes an Exchange API)

* Matrix / Riot (matrix is a chat server, Riot is the web client)

* Jenkins 2 (Continuous Integration / Continuous Deployment)

* FreshRSS (RSS aggregator)

Authentication is managed by a single LDAP service (openldap).

I also plan to test/deploy:

* Peertube (video hosting)

* Mastodon (micro-blogging)

My next goal would be to distribute this stack on more than one server, in order to improve availability.