I will not be explaining them, u can click on source to read more
1)The cat 2)water fall 3)the cowgirl 4)one up 5) the hot sit 6) spin cycle 7) stairway to heaven reverse cowgirl 9)pole position 10) face off 11) lazy man 12) David Copperfield 13) lazy girl 14) close for business 15) the pretzel 16) the G-whiz 17) the doggy style 18) the downward doggy 19) butter churner 20) get a leg up
check the link below for the remaining and the benefit and picture

source: http://www.menshealth.com/sex-women/45-sex-positions-guys-should-know