Complete (possibly official) list of "What is..." articles from the Notices of the AMS Does it exist online and where can one find it? (For example, these two sources are not official; is the longer one complete?)
 A: It seems that this is an official (and complete) list
https://www.ams.org/cgi-bin/notices/amsnotices.pl?article_id=whatis&article_type=gallery&gallery_type=whatis
A: I wrote to Allyn Jackson, who is in charge of this feature.  I reproduce her response below with her permission.

I can indeed answer this, and unfortunately the answer is no.
  Embarassingly, we don't
  have an online index for the WHAT IS column.  The Notices web site is rather
  primitive,
  and there is no natural place to put such a list.  We are hoping to do an
  upgrade soon,
  and this would include a WHAT IS index.
I knew about the list of WHAT IS columns at Cornell, but I didn't know about
  the other
  one at arminstraub.com.  I have my own list that I use in editing the
  column, and, like
  arminstraub, I have column #106 as Heil's "What is a frame?"  So it seems to
  me that
  the arminstraub list is complete, but I did not check every title against my
  own list.  The
  last column in my list is #110, so arminstraub is missing the 4 latest
  columns.
It is gratifying to know that there are some serious WHAT IS fans out there.
  Comments
  and suggestions are welcome and can be sent to notices-whatis@ams.org.

A: Assuming you have access to MathSciNet, a search for Title containing "What is" and Journal containing "Notices" seems to work pretty well. 
A: It seems they made a list in the meantime:
http://www.ams.org/publications/notices/whatis/noticesarchive
