IMHO, there is an excellent article in the American Alpine Journal's Accident Reports about a recent crevasse fall while crossing a glacier unroped.  The fallen mountaineer fell about 60ft, hit his head (no helmet), lost consciousness for several minutes, dislocated his should, and (all things considered) was extremely lucky.  He wrote a good article to help others either become aware of... or be reminded of... the potential dangers when crossing what looks to be a "safe" glacier.  I especially like his comment: "If you fall in a crevasse unroped, you fucked up."  The full article is short and worth the time to read it... http://publications.americanalpineclub.org/articles/13201213490