Vanessa:
        What do you mean by "Top Five."  Do you mean the largest?  The best
administered?  The highest attended?  The easiest to work at?
        To find a museum job, it might be best to first decide what you want
to do at the museum.  Promotions?  Development?  Business?  Volunteer
relations?  You might even be able to snag an entry level Registrar's
Assistant position (these tend to go to museum versus arts administration
folk, but not always).  After you've decided what you want, determine which
museums have this type of position, and then approach them pinpointing your
career interests in one of these categories.  Museum administrations are
usually broken down into departments, or at minimum, the positions are
subdivided by area of  responsibility.  You'll probably have to approach them
categorically.  ...  There are exceptions to every rule, of course, but I'd
approach it in this manner for all but the tiniest museums.
        You may also want to consider doing a websearch on communities that
you're interested in working and living in.  Pull up their museum websites,
take a look at how their administrations are organized, and pinpoint your
resume to a person and department.
        I hope this helps,
        Mike Radice, The Union Institute, New York City