Yahoo introduced a new twist to searching called Yahoo! Mindset.

The idea is that after you search for something you can view the results according to your mindset: whether you are looking for something more commercial or more informational.

They let you choose your mindset by a slider that dynamically changes the search results according to the position of the slider (very cool and intuitive).

This thing is not available on the regular Yahoo site, it is still in Beta and is part of the Yahoo Research Lab.