neutriNote - the original extensible Markdown + Math note app. Non-commerical. No lock-ins. Only 3 MB footprint & highly optimized. Designed for plaintext purists.

ImageCat is an Apache OODT RADIX application that uses Apache Solr, Apache Tika and Apache OODT to ingest 10s of millions of files (images,but could be extended to other files) in place, and to extract metadata and OCR information from those files/images using Tika and Tesseract OCR.

Elwha is a Java application for monitoring topics, sentiment and events on Twitter streams with the ability to generate notification messages before passing the presence of such events on to some additional workflow.