I use xscreensaver, here are my .i3/config entries:
exec --no-startup-id xscreensaver -nosplash &
exec --no-startup-id xautolock -time 5 -locker xscreensaver-command
-lock &
bindsym $mod+Pause exec --no-startup-id xscreensaver-command -lock
The first two start the daemons in the background. The last is a keybinding
to start xscreensaver on command. You may have to install xautolock, but I
believe it is in the repositories so that is easy to do.
I really like this video series:
https://www.youtube.com/watch?v=j1I63wGcvU4&list=PL5ze0DjYv5DbCv9vNEzFmP6sU7ZmkGzcf
The final video, part 3 'rice your desktop', talks about i3blocks. Bear in
mind that not all suggestions in this series involve free software. For
example, one of the fonts he recommends does not seem to be free. So make
sure to double check.
