I love the first comment on that post: It will be more of a pain than usual, but I will get the data. I always get the data.

- As mentioned: AJAXification the data makes it easier to grab.

- Convert text to images? I'll OCR it. http://code.google.com/p/tesseract-ocr/wiki/ReadMe

- Honeypot a random link? I don't scrape every link on the page, only links that have my data.

- Randomize the output? And drive your real users crazy?

I have found that the best deterrent to drive-by scraping is to not put CSS id's on everything. Apart from that, you'll need to put the data behind a pay wall.