Another option that has been removed is page previews, which displayed a longer snippet and a thumbnail for each search result. This feature has been replaced by Instant Preview, but you can no longer see all the thumbnails next to the search results.
When Google launched the sidebar, back in May 2009, it was the first time when powerful features like restricting the results to recent pages didn't require to visit the advanced search page. "We think of the Search Options panel as a tool belt that gives you new ways to interact with Google Search, and we plan to fill it with more innovative and useful features in the future."