ZK Spreadsheet is an open source embeddable web-based online spreadsheet that delivers the rich functionality of Excel within browsers using pure Java. (Moved to http://code.google.com/p/zkspreadsheet/ since ZK Spreadsheet 2.0)
Small, fast Java library for reading and writing CSV files
Java CSV is a small fast open source Java library for reading and writing CSV and plain delimited text files. All kinds of CSV files can be handled, text qualified, Excel formatted, etc.