If it is just for a first try to experiment with structuring those kinds of application, or if your needs aren't even that complicated, it can even be quite close to trivial sometimes. But it's hard to know what is out there, and how useful it would be. Things that I've done on the side that weren't too hard and even more fun than I imagined beforehand:
* Media Players (Video and Audio) with GStreamer (0.10 can be okay'ish, 1.0 is very nice so far)
* Text Editors (via Gtk-Source or embedded GVim)
* I've tried building a specialized browser with WebKit. Was also quite easily used, except that I gave up when trying to get the Flash plugin to run turned out to be not-fun. Others may have more motivation.
Note that I mostly try these things in Gtk2/3 with either Perl 5 or Vala. Python seems to have very good Gtk/GObject bindings as well, so that should mostly apply the same way. And I'm sure if you look at the Qt and Wx ecosystems there will also be many preexisting useful components, or ways to plug them in.
* Media Players (Video and Audio) with GStreamer (0.10 can be okay'ish, 1.0 is very nice so far)
* Text Editors (via Gtk-Source or embedded GVim)
* I've tried building a specialized browser with WebKit. Was also quite easily used, except that I gave up when trying to get the Flash plugin to run turned out to be not-fun. Others may have more motivation.
Note that I mostly try these things in Gtk2/3 with either Perl 5 or Vala. Python seems to have very good Gtk/GObject bindings as well, so that should mostly apply the same way. And I'm sure if you look at the Qt and Wx ecosystems there will also be many preexisting useful components, or ways to plug them in.