Xelem is a compact Java-library to read and write Excel files of type SpreadsheetML. It can produce sophisticated, intricate and complex spreadsheets from within any Java program. And, since the release of xelem.2.0, it can read xml-spreadsheets.
It's a free and handy text editor for both plain text files and formatted text files and printing. Since release 1.2.0 there is a tool for the conversion in PDF format. It's written in Java language so it's available for a lot of Operative Systems.
MacBibTk is a Mac compatible version of Peter Corke's tkbibtex (release 9), a BibTeX file editor and browser. BibTeX is a reference/citation system for use with LaTeX. MacBibTk runs on all platforms with Tcl/Tk ports.