CBB is a personal check book balancing utility for Unix/X.  

CBB is intended to be an open, extensible program.  It utilizes a
simple (tab delimited) data file format and is written entirely in
Tcl/Tk and Perl and contains no compiled code.  It provides a simple
interface for users to add their own reports, graphs, and external
modules without having to modify any of the CBB source.

WWW: http://gna.org/projects/cbb/