So far only 11 confirmed cases of Guinea worms  this year. This is amazing, given that there were about 3.5 million in 1986.
This is not the only attempt to eradicate diseases . So far humans have already managed with two diseases: Smallpox and Rinderpest (which doesn't affect humans).
It seems like Polio is on a similarly good path: so far only 36 cases this year (with an estimated 400,000 in 1980).
Yaws  is another disease that is on WHO's list. According to the their roadmap, the elimination should be achieved by 2020. It's almost sad that we (humans) aren't able to do it faster. Quoting Wikipedia: Yaws is a relatively easy disease to eradicate. Humans are likely the only reservoir of infection. A single injection of long-acting penicillin or other beta lactam antibiotic cures the disease and is widely available; and the disease is highly localised making case tracing relatively easy.
The fourth, and last, disease that humans are trying to eradicate is Malaria. Although it's still endemic in Africa it has already been eradicated from places like Europe and the US (where it was once common). From what I can tell there is still no perfect way to achieve the eradication goal, but a lot of research is put into it (like vaccines). And there is always the "easy" way of making sure that mosquitos don't bite you. As of 2012, the Global Fund to Fight AIDS, Tuberculosis and Malaria has distributed 230 million insecticide-treated nets.