ZK Spreadsheet is an embeddable Ajax spreadsheet that delivers rich functionalities of Excel within browsers using pure Java without the need for any plugins. Version 3.0 is now officially released with an overhaul for simpler API, new features, functions & bug fixes!
Release note: http://www.zkoss.org/product/zkspreadsheet/releasenote/3.0.0
New features: http://books.zkoss.org/wiki/Small_Talks/2013/November/New_Features_of_ZK_Spreadsheet_3.0.0