Is there a source for the history of ritual suicides? It seems to make news lately (Jonestowns, heaven gates,…) but I was looking for an extended list . kind of morbid I know.
Well, your wording led me down a slightly different path.This Site deals with the Ritual OF Suicide.
Your O.P. is really asking about Mass Suicides, not the rituals, is that right? You named Jonestown as an example. Try This study of recent mass suicides. Additionally, you can [url=“http://detnews.com/1997/nation/9703/28/03280127.htm”]Read This Article On Mass Death.
The second listing on This Page offers a sociology paper studying Mass Suicide through the ages.
Google. Ten minutes. Use your Web, friend 
Cartooniverse
Here’s a thread (albeit a short one) on hara-kiri
http://boards.straightdope.com/sdmb/showthread.php?threadid=50822