Dansko shoes, particularly the professional clogs (worn by all the nurses in my local hospital ICU, by the way) have the BEST arch support in the world, in my opinion.  I have Dansko shoes in four colors, plus several different styles.  I wear a size "39" (European sizing), which is somewhere between a woman's 8 1/2 and 9.  The only drawback (other than the fact that they aren't very sexy) is that the thick rubber sole (which helps give the shoe the arch it needs) tends to cause me to trip and sometimes I almost twist my ankle on hardwood or tile, so be aware of this possible problem if you order a pair.  As noted above, I own a lot of Dansko shoes, so don't let this problem stop you from trying a pair.

If you have plantar fasciitis or a very high arch that tends to "fall" or otherwise hurt, try Dansko, Merrell and Nike's Shox (especially the Navina model).  Recommended!