Just a quick one today - the humble hyphen. You may know this already, but if you don't this will no doubt be very handy to know. Many commands bring up a dialog box, such as the HATCH command. But, if you preceed the command with the hyphen character, this will usually force input via the command line. So, using -HATCH will invoke the HATCH command, but you'll have to control it via the command line. This can be extremely useful, expecially in combination with other tips I've posted (such as copy and pasting commands from Excel).
What people sometimes don't know is that using the hyphen to force command line entry can also sometimes reveal extra functionality that isn't normally available through the standard interface. Take the PURGE command for example. Using -PURGE allows you to dig a bit deeper, and purge a few extra things such as loaded applications.
Hope this little quick-tip helps someone!