We applied online via the e-Fasttrack option for an Unmarried Partner Visa. [Unmarried Partners of same-sex (and I would think, heterosexual couples too - but don't quote me on that) are given the same rights as spouses.] We used our credit card online to pay, printed TWO copies, printed out the email saying that payment had been processed, and took that and our other documentation/evidence to Chicago. Very easy!