I have a subdirectory in my home directory named bsd where
I like to keep all sorts of tips I run across or discover
for myself experimenting around with my system. Since I
have two OpenBSD boxes, I like to keep the bsd directories
synchronized. When I edit a file and save it, I don't have
to get out to make sure the file is on the other box too.
I can sync the directories by doing this while in vim:

:r! rsync --rsh=ssh -agrtv ~/bsd/ user@computername:bsd/ > /dev/null 2>&1

:r! allows me to run an external command.
rsync is used to synchronize the source & destination directories.
--rsh=ssh makes sure ssh is used for security.
-agrtv are rsync delimiters. RTFM! READ THE FINE MANUAL for them. ;)
~/bsd/ is the source.
user@computername:bsd/ is the destination networked computer with
bsd as the subdirectory.
> /dev/null 2>&1 stops the output of the command line from being
outputted to the screen, in this instance, into the file I'm editing.