The following list shows some of the libraries and programs that are using cairo. Additions to this list are quite welcome.
Snippets with screenshots
Øyvind Kolås has put together a great little page of samples showing how to draw useful things with small snippets of code.
Cairocks is a small library of useful, common Cairo routines. Examples for using it with cairo-gl and SDL2 are also available. A cairocffi-based Python3 companion module named cairockscffi is also available.
Bezier gradients, also known as type 6/7 gradients in PS/PDF parlance, are incredibly power tools. Using a patchwise 2D cubic Bezier surface allows them to construct any of the lesser gradients such as linear, conical and radial, and the flexibility to do so much more. One example, Adrian Johnson gives is the ability to create realistic shading of a complex object:
Mike Hearn wrote a very simple demo of how to make partly transparent windows with GTK+ and Cairo, and MacSlow has written a more complete example that uses the new XShape extensions to make the transparent areas click-through.
MacSlow also provided a little demonstration of using cairo-drawn graphics as dynamic textures for OpenGL. You can check out that particular example with:
git clone git://people.freedesktop.org/~macslow/gl-cairo-cube
svn checkout http://gtk-gl-slider.googlecode.com/svn/ gtk-gl-slider-read-only
Further examples regarding cairo, glitz and OpenGL are described on the cairo and OpenGL page.
A pycairo example showing how to use librsvg on windows: cairo rsvg and python in windows
A small physics / blob simulator using Cairo and SDL for rendering: blobsallad
The Xlib page outlines using Cairo with just Xlib to make a simple GUI demo.
A multi-threaded animation tutorial with cairo and GTK+: threaded animation with cairo
A nice vector animated clock video
An explanation of animating graphics with easings
The getting started with graphics http://www.getlazarus.org/forums/viewtopic.php?f=18&t=35
Cairo in motion is a small Cairo C__ in FLTK1 example of animation along spline paths.
Toolkits based on cairo
Cairo support is integrated into the GTK+ widget toolkit as of version 2.8.
Cairo is one among many GNUstep display backends.
Cairo has been used as the basis for the System.Drawing and System.Windows.Forms (a.k.a. Managed.Windows.Forms) namespaces in Mono's class library since the early creation of Cairo.
The SWT widget toolkit wraps cairo for its advanced graphics API on Linux as of version 3.1.
Papyrus is a 2D canvas (scenegraph) library which renders using cairomm (and thus cairo). A companion library, papyrusgtk, provides a set of gtkmm widgets that use a papyrus/cairomm/cairo stack for drawing.
Ada industrial control widget library for designing high-quality instrument dashboards is based on cairo.
Matplotlib is a 2D graph plotting library for Python. It supports a cairo backend.
gnuplot is a 2D and 3D graph plotting utility. Since gnuplot 4.2, it has had an interactive terminal written with the wxWidgets library, and this terminal renders the plot with cairo. Mainstream CVS of gnuplot also outputs to pdf with cairo.
PLplot is a 2D and 3D plotting library with several cairo device drivers. Currently these include xwindows, ps, pdf and png.
slope, a C charting library
librsvg is a SVG rendering library supporting a large subset of SVG 1.1.
Network Improv wrote an SVG Scene/Canvas Library which renders using cairo.
Other projects and programs
Roadster, cairo-based mapping program
Smrender, A Rule-based Renderer for OSM Data
GTK Cairo canvas: plans, experiments, interest
goocanvas: a canvas widget for GTK+
Sven Herzberg has written a GTK+ Cairo canvas for Criawips (see also: http://www.blaubeermuffin.de/svn/libccc/trunk/ChangeLog)
Alex Larsson (Redhat) has done some preparatory work (no further plans for the moment)
Manuel Cerón is working on UMLCanvas# 2.0
Rick Vinyard has created Papyrus, a C++ canvas (scenegraph) library. The papyrusgtk library provides gtkmm widgets that use a papyrus/cairomm/cairo stack for drawing.
Beast (link broken?) is working on a cairo canvas.
Jean Bréfort is interested in a gtk cairo canvas for GChempaint
Samuel Abels' ccanvasmm
Bruno Coudoin is interested in a gtk cairo canvas for Gcompris
Tom Cato Amundsen is interested in a gtk cairo canvas for GNU Solfege (link broken?)
Mark Van den Borre is interested in a gtk cairo canvas for a visual MusicXML player.
Dave Robillard is interested in a gtk cairo canvas for Om
Gustavo Carneiro is interested in a gtk cairo canvas for gNumExp
Chris Spencer is interested in a gtk cairo canvas
Nicola Fontana is working on ADG (link broken?), a non-interactive cairo canvas
Juan Manuel Mouriz also is working on sanaviron, a 2D drawing engine fully written in Python for represent composite vector graphics. This is essentially a GTK+ Cairo based canvas.