You may know that you can execute commands from inside of vim, with a vim command:
:! ruby do.rb
which will execute that code, and then - upon hitting enter, return you to your workspace.
Another nice one, is you can execute the exact same command with:
I use those a lot, but I just learned you can send the current buffer via a pipe (even if unsaved) into a command like this:
Pretty nifty, huh?