Ever hear of disease? STDs are prevalent among heterosexuals. They, and many other diseases are almost the rule among homosexuals. Whole arrays of disease are prevalent in those that practice anal sex that aren't in those that don't.
The state has a legitimate interest in differentiating these behaviours and discouraging some - especially since many infected by these various diseases allow them to more easily become carriers of other diseases (Then there's the whole idea of public health-care).
Sodomy hurts all tax payers. As tax payers we are paying out the ass (as opposet to in the ass) huge sums of money to treat and attempt to find a cure for AIDS. If the people participating in high risk behavours, such as sodomy, take all of the responsibility I wouldn't mind the laws being repealed. Let those who kill others via AIDS pay for their actions. Don't take money from me to pay for their perverted practices.