Hey all,
I’ve made an exporter for sketchup which first exports the textured faces of a model as a text file, then a binary which reads those faces and exports them as an .obj file. The difference between this exporter and others is that it culls any default or color materials, so that only textured faces are exported. This means you do not have to worry about flipping the backfaces of your model, or about exporting unnecessary geometry. This is very useful for rendering, video games, etc.
The readme is essentially pasted on my site, so you can read through the steps and see if it interests you before you install the program. I just released it, btw, so there may be bugs in the export. If there are, please message me or post them here, preferably with instructions on how to replicate it. One known issue is that faces must be triangulated with a utility beforehand or else complex faces may come out with missing triangles. For the triangulation, I recommend using this plugin by TIG.
It should not change the behavior of Sketchup in any way other than adding an option to the "plugin" menu.
Anyway, I've released this under the BSD license, but I would appreciate it if you linked back to my site and left the license intact if you use this utility in any of your projects.

Newest version, neatly places the functions in a submenu and adds the "Normalize UVs" option to export perfectly square and proportional UVs. Source and binary included for c++ poriton.