I have created several landing pages for a campaign each of which includes a special offer. I only want people who find this landing page via adwords to get the special offer. So I don't want the landing pages to be indexed in Google or elsewhere and was thinking that I should just include a robots noindex tag. Would this negatively affect my Google Adrank?
As long as the pages are not linked from anywhere then you don't need to worry about it. But you should. robots.txt exclude your /ppc/ dir. Noindex, noarchive and nofollow your landing pages too.
Remember there are 2 kinds of robots which google uses to crawl.. GoogleBot, MediaBot, AdsBot... when you install a robots txt file ensure you allow Adsbot but not allow Googlebot.. Cianuro is right that dont link it from elsewhere...
There is one link on the landing page to the main website. Is there any reason I should include nofollow? I'm happy for the robots to go to that page.