Practically its difficult to get a sponsor without a job if you are talking with desi consultancies i think same applies for american.
But if you pass interview may be some one may be interested in sponsoring you.
Try these sites
http://classifieds.sulekha.com/us.aspx
http://www.corp-corp.com/
craigslist in your area
dice monster http://www.careerbuilder.com/  as you know