Maybe dia will be to your liking. It's quite similar to Visio, if you're familiar with that. There are both Debian and Ximian packages for it:
Package: dia Status: install ok installed Priority: optional Section: graphics Installed-Size: 10836 Maintainer: Ximian, Inc. <[EMAIL PROTECTED]> Version: 0.88.1-ximian.2 Depends: libart2 (>= 1.2.0), libc6 (>= 2.1.2), libgdk-pixbuf2 (>= 0.9.0), libglib1.2 (>= 1.2.0), libgtk1.2 (>= 1.2.0), libpng2, libpopt0, libxml1, libz1, xlib6g (>= 3.3.6-4) Description: A GTK+ based diagram editor andcharting tool Dia is used to draw diagrams, graphs, charts, and so forth. This is an early version, but the program is fully usable. In this version there is support for UML static structure diagrams (class diagrams), Entity-Relationship diagrams and Network diagrams. Diagrams can be exported to postscript. Noel
