@fineleg, I used the following documents for my parents who visited me twice, last one being couple of months ago.
1. Letter to the consulate requesting issuance of visitor’s visa
2. I-134 affidavit of support (original) - notorised copy
3. Visa approval copy ( I797A )
4. Your Passport copy ( Entire passport )
5. Your I-94 copy
6. Letter from Employer ( original ) stating that u've been working with them for so and so years.
7. Last 3 months salary slip
8. Last 2 years tax return (USA) W-2
8. Last 3 months bank statement
9. Certificate of title ( Car ) - Just an additional stuff to support ur financial credentials,not required though
10. Invitation letter from your
For further info, u can refer to
http://path2usa.com/immigration/visitorvisa/visitor_visa.htm