This extension consists of two components: a search box replacement and a context menu item for creating new search engines ('lookpicks'). What's special about the search box is that it fetches the search engines from a server at lookpicking.com, where you can also set up your personal list. This means that you can use your collection of search engines from any computer on the web, and that you can share your search engines and use others' as well. Just type some letters of the search engine you want, and it will be shown as an autocompletion-choice. Select it and perform your search.
The context menu makes adding new search engines to your list as easy as right-clicking on any text field on a web form, selecting "Lookpick this..." and choosing a name for the new entry.
But all these search engines don't mean that you can't just type your query in the search box without selecting any search engine upfront: if you do so, you will be taken to your default search engine's results that you can specify at lookpicking.com. Moreover, you can easily jump back and forth between the browser's standard search field and the lookpick search box.