Sindice.com: A Document-oriented Lookup Index for Open Linked Data
Developers of Semantic Web applications face a challenge with respect to the decentralized publication model: how and where to find statements about encountered resources. The "Linked data" approach mandates that resource URIs should be de-referenced to return resource metadata. But for data discovery linkage itself is not enough and crawling and indexing of data is necessary. Existing semantic Web search engines are focused on database-like functionality, compromising on index size, query performance and live updates.