So the hint ... most sites are gregarious and will cookie you just to remember you. So I found the ~/Library/Cookies/Cookies.plist file and although I loaded it up in the Property List Editor program, it was structured such that the sites that created my 1,200+ cookies couldn't quickly be read. So I resorted to grep poster Cookies.plist (from within the directory in the Terminal). This got me a list of the 12 sites with 'poster' in the name that I'd ever visited. From there, I quickly found my previous shopping experience (I had saved a cart).
Of course, opening this file in any reasonable text editor -- TextEdit, vi, emacs, or even a repetitive search in Property List Editor would work, but grep was suitably quick and dirty.
Not really a big hint, but worth sharing for novices to the Unix world...

