PadMapper is really just an alternative view of Craigslist data. I don't see any functionality that couldn't be implemented purely on the client side, using for example Javascript executed as an extension or a bookmarklet. This client-side code would execute Craigslist searches, scrape the results, and render in the form that PadMapper does today. While the TOS can disallow other businesses from such scraping and re-publication, I can't see how Craigslist has any legal standing to disallow users from doing that for themselves (in which case it's personal use, not re-publication), whether they do so manually by jotting down listings on a notepad or automatically by running a script on their computer.
Can anyone give solid arguments against what I am suggesting?