Matt Williams' quest for a tool to extend the Windows Clipboard when working at the Command-Line seems to be over. To quote Matt:
CLCL seems to be exactly what I was looking for. I tried Shell Toys XP and while it has a clipboard management tool, it also has a boatload of other stuff. I just want the clipboard tool. Plus ShellToysXP is very slow, taking about 2 seconds for the clipboard+ tool to show up. CLCL comes up in about a third of a second. ClipX seems to do just as well, but since I tried CLCL first, I might stick with it.
The full list of tools suggested is: