The Register has an article about one of the patents up for sale in the latest Ocean Tomo auction that could potentially be used to sue pretty much every web 2.0 company.
The patent, for "a global sideband service distributed computing method" is described by its owner as being a core component in any kind of AJAX implementation, and lists out basically everyone as infringing.
Any site that uses AJAX? Yup. Google, eBay, Yahoo?