You will enjoy these great general reference works on funeral and death customs that cover more than one culture or people.  Below is a brief annotated list of those titles I found helpful.

¤ Taylor, Richard P. Death and the afterlife: A cultural encyclopedia. Santa Barbara, California:
     ABI-CLIO, 2000.

A fantastic reference work describes the customs and traditions about death and funerals from many cultures.  A review in The Library Journal called it  clear and well-written with articles that cover most major religious and cultural traditions from prehistoric to modern times.  You may be able to access this encyclopedia online if your library participates in the netLibrary program.  Check with your librarian or at http://www.netLibrary.com/urlapi.asp?action=summary&v=1&bookid=56906

¤ Counts, Dorothy A, and David R Counts, eds. Coping with the final tragedy : cultural variation in
     dying and grieving . Amityville, NY: Baywood Publishing Co. , 1997.

A bit of an unusual perspective on death and funeral customs. It contains many different viewpoints on how different societies, in one case even a 'society' of primates deals with death.

¤ Barley, Nigel. Grave matters : a lively history of death around the world. New York: Holt, 1997.

 A sometimes irreverent look at funeral customs around the world.  It includes some informal customs as well as more traditional and culturally accepted customs.  It tries to take a light hearted look down the path we all must one day go.

¤ Perl, Lila. Dying to know - about death, funeral customs, and final resting places.  Brookfield,
     CT: Twenty-First Century Books, 2001.

 This is the second best reference, after Taylor's encyclopedia, I was able to find locally.  It is an amazing little book, just shy of one hundred pages.  Shelved with the young readers non-fiction collection this book written for grade school students deals with death and funeral customs in a clear and straight forward manner.  Perhaps it is the innocence of children we lose as we grow up, but this book geared for children provides much more factual and entertaining information than many of the larger tomes geared toward adults.
 

There are some excellent videos which look at funeral customs in their coverage of death.

¤ Death an overview. Sleeping Giant Productions. 1998. Videocassette. Annenberg/CPB Project.

This ten cassette program is available in many libraries both academic and public as it is used in the PBS Adult Learning Service.  Death and Dying are the subject of the program, however funeral customs are discussed on several of the tapes.

¤ Champlain, Joseph. Death and life: Preparing for the Catholic Funeral Mass. 1997. Videocassette. Ave
     Maria Films.

While filmed in the United States the Catholic Funeral Liturgy is practiced worldwide with little variation.  The author of the videotape, a Catholic priest, discusses how the funeral service and the Church comforts those in mourning.  This videocassette can often be located through Catholic Diocesan libraries; each diocese has one. Any Catholic priest should be able to assist you in locating the library or the video.
 

Oddly enough there are quite a few periodicals about funerals.

¤ The Director, a publication of the National Funeral Directors Association (USA) is available online in digest form.

The magazine deals primarily with business and professional issues facing funeral directors in the United States.  Occasional articles discuss funeral customs and how funeral directors may adapt their practice to meet the needs of those with different needs. "Funerals are a Last Rite of Passage, and a Service to Those Who Live" was an article in a recent issue.

¤ Many periodicals are available in other languages including Spanish, Czech, Polish, German, Afrikaans, French, Danish, Dutch and Italian. Ulrich's Periodical Directory lists three pages of funeral related periodicals. Ulrich's is available in most libraries as it is the de facto standard periodical reference.
 

Some World Wide Web resources are available.

¤ A bibliography of funeral and burial practices is available at http://wings.buffalo.edu/academic/department/anthropology/Documents/deathbib .  Unfortunately it is a bit dated, November 1994, however some interesting sources are contained within the bibliography.

¤ An exceptional resource that has links to the funeral rites of many cultures is available at http://www.thefuneraldirectory.com/ancientrites.html .  Although this is a commercial site that actually adds to the authority of the information on the site. The links on the site are for the most part authoritative as well.
 

Some other sources that you may find helpful are:

¤ Bradbury, M. (1999). Representations of death: a social psychological perspective. New York:
     Routledge.
       This is also available through netLibrary at http://netlibrary.com/ebook_info.asp?product_id=60924.

¤ Kalish, R. A. (1980). Death and dying: views from many cultures. Farmingdale, N.Y.: Baywood
     Publishing Co.

¤ Harrah, B. K. (1977). Funeral service: a bibliography of literature on its past, present, and
     future, the various means of disposition and memorialization. Lanham, MD: Scarecrow Press.

¤ Huntington, R. (1979). Celebrations of death: the anthropology of mortuary ritual. New York:
     Cambridge UP.

¤ Matsunami, K. (1998). The international handbook of funeral customs. Westport, CT: Greenwood Press.

¤ Hockey, J.A. (2001). Grief, mourning, and death ritual. Philadelphia, PA: Open University.

¤ Rites of death. FIlmRoos.Inc. 1996. Videocassette. Arts and Entertainment Network.

¤ Crypts, coffins and corpses. A & E Home Video. 2000. Videocassette. Arts and Entertainment Network.