twyg lets you visualise arbitrary tree structures in a pretty way. The appearance of the tree (layout, color, node, connection shapes, etc.) is fully controlled via configuration files in a generative way. This means that almost all visual properties of the output can be controlled by expressions that depend on the characteristics of the tree (e.g. the color or shape of a node can be a function of its hierarchical position in the tree). This allows for crafting very flexible configurations that can be applied to trees of arbitrary size and complexity. It supports the Cairo and NodeBox1 rendering backends.
StabieDraw is a simple 2D vector drawing program for creating illustrations in PDF format. The program is based on an IC layout editor and the interface will probably be most familiar to people in the IC industry. It has a Tcl interface for creating and modifying the shape objects as well as a traditional interactive GUI, though it is almost required to put the window manager into focus follows mouse mode to use this program. Objects include rectangles, paths, polygons, circles, donuts, references, and programmable objects.
ImgView is a simple image viewer for Unix-like systems. It is free from menus and other GUI gadgets, and controlled primarily by the keyboard. It supports the following image file formats: XBM, PBM/PGM/PPM, GIF, JPEG, TIFF, PNG, and PCX. It supports RGB, Gray, and CMYK ICC profiles in JPEG, RGB and Gray ICC profiles in TIFF and PNG, and RGB ICC profiles in GIF.