Fast etags for JSON.
Use the elasticsearch-js client with Amazon ES
Excel (XLSB/XLSX/XLSM/XLS/XML) and ODS spreadsheet parser and writer (extended to enable read/write of cell formats with xlsx files)
HTML to PDF converter that uses phantomjs
Assert-style non-intrusive type checking.
Feature rich priority job queue backed by redis
Full featured Promises/A+ implementation with exceptionally good performance