A.nnotate.com allows you to annotate documents and images online. You may also collaborate on documents and index files. A.nnotate.com supports PDF and MS Office file formats, and runs on all common web browsers.
Solr is an open source enterprise search platform from the Apache Lucene project. It operates as a standalone full-text search server within an appropriate servlet container, such as Tomcat. Solr uses the Lucene Java search library at its core for full-text indexing and search, and has REST-like HTTP/XML and JSON APIs that make it easy to use from virtually any programming language.