Attached Link: http://sketchuptips.blogspot.com/2007/01/wavefront-obj-exporter.html

Well, I don't use it (yet) and I'm not certain, but I think you may find a free "Ruby" (what they call a sort of plugin) that may be able to export to .obj. However, I don't know where to point you for those ;)

(edit). I found this link, however I can't speak for the results. I just found it on an internet search.

Laurie