Expedia increased their profits by $12m by deleting one field from their registration process

"The following test from Expedia shows how understanding how your users interact with your forms leads to conversion rate gains.
[In the Expedia experiment] they simply dropped the “Company name:” field and that increased their site PROFIT by $12 million a year according to Silicon.com.
Why was changing this field so critical?
Because that single field broke the flow of their entire UI:
When visitors see the “Company” field, they were confused.
Visitors thought Expedia meant they should put in their Bank name.
Users then put their’s Bank’s address into the billing fields.
This led to failed transactions, which led to abandons."
Source:  Conversion Voodoo blog, November 2011
Note - I can't the Silicon article they reference - broken link
But...  Here's an earlier link, suggesting that the story is originally from late 2010