Apple's Accordion Fold Interface
This Bivouac Interface Hall of Fame entry from Apple is an outstanding example of reducing perceived complexity and helping pull users through otherwise overwhelming transactions.
By collapsing most of the information entered in one section of the form into a strata, Apple keeps users grounded but reinforces a sense of progress throughout the checkout process. Along the way, a yellow prompting box appears next to the unfilled required fields, indicating what users must enter to continue. Stratification of information in clear zones serves as landscape "mile markers," allowing users to sense how far along they are in completing the tasks.
From Luke Wroblewski on A List Apart. Thanks to Arjun for passing this one along.
