I’d like to turn it around and ask you what you have self-hosted? Always curious what people have chosen. :)
(not OP) I’m self-hosting Camlistore for backups (which has been working well so far) and a hacked-together RSS reader (because so many feeds only include a summary and a link to click through).
I host my mails (OpenSMTPd as MTA, Dovecot as MDA until the OpenBSD-developers show some mercy and come up with their own implementation of IMAP), my website/s (static placeholder and blog, both via httpd, blog’s Wordpress), instant messaging (XMPP via Prosody, used to run Mattermost for a while), my backups (Arq, to three different physical locations), file synchronisation (recently switched to Nextcloud from ownCloud), torrents (via Transmission - and yes, really not for piracy), .. I’m sure I forgot something.