Mac OS X Leopard only: You wouldn't think that Leopard's new Quick Look feature would work anywhere but from Finder, but you'd be wrong. From the command line in Terminal, you can invoke Quick Look to preview the contents of a file. Tips web site Mac OS X Hints details how: the command is
qlmanage -p somefile where
somefile is your document. As Mac OS X Hints recommends, setting up an alias (
qlf, perhaps?) is a good way to save your typing fingers when reusing this technique.