What an awesome tool that was! You could preview images from Craigslist ads without clicking through to view the entire ad. I was very stoked when this came out because it was so easy to quickly scan the listings to see if there was anything worth pursuing. For the most part I don't even look at ads that don't have pictures so that tool really cut to the chase for me. Then Craig had to go and put the kibosh on the whole thing and well that sucked.
But now there's this nifty Firefox plugin that essentially does the same thing. It's just a browser add on so hopefully Craig can't kill it like he did with Listpic.
Ad preview extension for Firefox.