Nice thread and interesting solutions, I'm more like bsdkeith myself:)

To-do-lists:
I use alias todo='vim ~/todo'. I also have note and todo functions from https://wiki.archlinux.org/index.php/Bash/Functions, but I tend to forget about them.

Contacts:
No managmet. In my email programs.

Calendars:
Mainly cal. I installed calendar.vim, but I lack the discipline to use it.

Note taking and storage:
Used to be paper notebooks and chaotic files on computers, lately I'm trying to write as much as I can in my vimwiki.

Email setups:
Mainly mutt. For one account I use Mailpile, because I wanted to try it out. For some accounts I just use the webmail interfaces.

Device synchronization:
Similar to bsdkeith. I use an external HDD, and put files I need on a USB flash drive o.O I have pydio on a server, which I rarely use.