:r file | Read in contents of file after cursor. | 
:r !command | Read in output from command after current line.  | 
:nr !command | Like above, but place after line n (0 for top of file). | 
:!command | Run command, then return. | 
!object command | Send buffer object to UNIX command;
replace with output. | 
:n1,n2! command | Send lines n1 -n2 to command; replace with output. | 
n!!command | Send n lines to UNIX command; replace with output.  | 
| !! | Repeat last system command. | 
| :sh | Create subshell; return to file with EOF. | 
| CTRL-Z | Suspend editor, resume with fg (not in all versions). | 
:so file | Read and execute commands from file. |