Santa Clarita, California, will use Cumulative Voting for city council elections starting in 2016. See this story. The city currently elects city council members at-large, but the city had been sued under the California Voting Rights Act because the current system does not seem to permit Hispanics to win seats on the council. Under the new system, there will be no districts, but each voter will have three votes, and will be free to give one vote to three candidates, or three votes to a single candidate, or two votes to one candidate and a single vote to another candidate.
Santa Clarita has a population of 180,000 and is the fourth most populous city in Los Angeles County. It is north of the San Fernando Valley. Thanks to Rick Hasen for the link.