I've been having fun with a new search engine for graphs call Zanran. Zanran crawls the web and classifies content in a number of formats including PDF, excel, html and image. Resources that it classifies as either graphical presentations of data (time series, pie charts, bar graphs, etc) or tabular data it indexes. When you search over this data set, the results are charts and tables containing data relating to your query.
The site, like any sensible engineering endeavour, is very focused in terms of scenario. There is a simple search / response interaction similar to a web search engine.
One can interact with the search results by hovering over the icon on the left (which also indicates the type of the result document, be it PDF, excel, etc.). This action brings up an overlay which includes the page or other document element containing the data.
However, as it has opted for the same interaction paradigm as a search engine, it is forced to optimize for relevance as its core competency in connecting users to data (other models might include browsing by categories, browsing by source, or even browsing by the shape of the data as done by Eiodosearch). This is where the site has some real challenges. The site also suffers from some failures. Searches for 'per' and 'for' provide a server side error of some sort (possibly due to a high hit count?).
At anyrate, I see Zanran as being somewhat aligned with the philosophy behind d8taplex in terms of data sources - the wild web, rather than being limited to open data. However, it is focused on a different user scenario (get the user to a source with the data rather than get the data to the user for interaction).