I came across EidosSearch recently - a company founded by Steven Zhang and David Kedmey. Their product is a visual search engine for time series. You can select an exemplar data set (part of a time series) and it will return close matches to that time series from an indexed data set. While I don't think this is a novel idea, it is perhaps the first time I've seen it implemented with any degree of elegance.
Their homepage (linked above) has a good video introduction explaining what they do.