Search engines suggest alternative keywords when you mistype keywords.
I was looking for a Wikipedia article on Liskov substitution principle. I came across this when I was reading about Design By Contract elsewhere and the article had 'mistyped' the phrase as Lyskov substitution principle.
I first entered it in my Firefox Wikipedia search engine plugin and got no results. My next target was Google and this is what I got:
Not knowing that I had mistyped the phrase, I did not click on the suggestion. I was in fact surprised that Wikipedia does not have an article on this!
Then I searched in Yahoo and this is what I got:
Wow! I had indeed mistyped the phrase and Yahoo turned out to be intelligent in guessing what I was interested in.
Google's approach is like: 'I guess you have made a mistake, but I am not sure, here is the result for what you typed. However, I think you are looking for this.' Yahoo's approach is: 'I guess you have made a mistake and this is what I think you are looking for, if you are interested in search results for only what you typed, click here.'
I am not sure which approach is better, but I definitely like Yahoo's approach because it saves me a page load and a click.