This very tiny webservice is designed to fetch yearly item counts for a given search from the PubMed database. By comparing these counts to the counts of all PubMed items in a year it is possible to calculate the proportion of items for a search year over year and thus get sense of the real trends for publications on a given topic. Numbers from this service feed into PubMed by Year

More information in my blogpost The Littlest Webservice.