Gabe's come up with the solution to my screen-capture woes. By holding down the controlkey while hitting shift-cmd-4, you get the screen capture on your clipboard. ToyViewer has a shortcut, shift-cmd-v, that makes a new window with the clipboard contents on it. Shift-cmd-j saves the foremost window as a JPEG. That's one step fewer than I've had to take to date -- w00t!