STD Friends is a site that caters to people with STDs and has been around for many years. It is one of the oldest and most well established sites in the STD dating niche.
My search for local matches returned some attractive potential dating partners, and it appears that they have new members joining regularly.
There are updated articles and 2.0 features but the design is a little outdated. Regardless the most important thing is the volume of members and the ability to communicate effectively with them. STD friends definitely excels in this regard and has a significant edge on the competition.