Nice thread!

To-do lists

Since I really don't have time to pull out my laptop or sit down at the desktop just to look at a to do when I'm on the go, I just use Google Keep on my phone for quick to-dos. It's super simple.

Contacts
I make a habit of purging contact information if I haven't spoken to someone in six months. I only have about 8 contacts in my phone atm. I figure I don't really _need_ to keep their stuff around, and if we run into each other after six months I can just get it again from them.

Calendars (and notifications)
I use the calendar offered by Fastmail (my email provider). It's synced with CalDav to my home computers and phone.

Note taking and storage
alias note='vim ~/notes' <--- notes is kept in git, synced around to all machines

Email setups (this should be fun!)
I use mutt with msmtp and mbsync for syncing over IMAP. It handles several different accounts for me, plus a dozen or so mailing lists. I can't recommend mbsync highly enough, it's much faster and more reliable (in my experience) than offlineimap. I have a cron job that runs every 5 minutes to sync up all the mails.

Device synchronization
Just recently I setup a VPS running Seafile for syncing school assignments or pictures and government secrets. It's fairly new so I don't have a good flow around it, but I'm really liking it a lot, it handles syncing better and less overhead than Owncloud for me. I also use git+stow to manage all my dotfiles. I have a quick script that runs on new setups to git clone and stow all the things - 30 seconds and I'm ready to go anywhere.