While it won't replace search engines for certain information WolframAlpha is an amazing resource for finding factual data, which makes it perfect for homeschooling parents! My husband shared the site with me earlier today after reading about it in Popular Science Magazine's Best of What's New 2009 article and I was incredibly impressed!
The site answers specific questions, as opposed to supplying information on general topics.
Solve Mathematical Problems
Explore Places & Geography
Learn About Life Science Topics
The list goes on.......
I hope other homeschooling parents utilize this awesome site!