Thought-provoking article at the Social Patterns blog about Google UI Snippets. Briefly, a ui snippet is a link within a site presented as part of a serp.
Michael Nguyen thinks the selection process has something to do with traffic data, presumably acquired from the Google toolbar:
“If you are using the Google Toolbarâ€™s advanced features, when you visit a web page, the toolbar sends Google some information including the url of the page. This data could be used to track linking data that Googleâ€™s crawler can not successfully crawl. In other words, with the Google Toolbar, you are Googleâ€™s crawler.”
Michael backs up his comments by comparing Alexa data, concluding that many siteâ€™s snippet links closely resemble Alexa traffic stats.
Interesting, eh. On a related note, does anyone have any other examples of curious toolbar “crawling” ability?