Well, I just did a little study of my own regarding years with tropical systems individually responsible for >100 deaths. I used the Weather Underground archives as my resource. I only went back as far as 1933, and here is what I found:

Only ONE year had more tropical systems responsible for 100 deaths each than 2004. That was 1944, which had four tropical systems each kill more than 100 (216, 390, 216 and 318 respectively).
One other year had 3 different systems, each of which killed more than 100. That was 1955 (Diane-200, Hilda-304 & Janet-681).

I noticed that the Weather Underground archive included non-named tropical and subtropical systems in their data base. Therefore, I feel it is valid to include the May storm this year that struck Haiti.
So far, we have had 3 systems each responsible for >100 deaths: the Unnamed May system (3,000), Hurricane Ivan (118 at last count) & Hurricane Jeanne(possibly as many as 1,700).
Needless to say, 2004 is shaping up as one of the truly bad hurricane years. While many individual storms in the past have been responsible for high fatality counts, there have only been 2 other years with as many storms responsible for >100 fatalities. With another 2 months in the 2004 hurricane season, 1944's record might also be broken.

--Lou