The Leukemia one just made me feel uneasy..and I thought I actually have no idea whether the money ends up there or not. The following day I got a phone call from Guide Dogs...who I also have supported in the past, but it actually sounded like the same person who had rung me the day before. It may or may not have been. And of course we all know about call centres.
Finally I rang and registered with http://www.donotcall.gov.au/ so I will be interested to see if it works. Haven't so far had any more calls after having had at least one every day for the last week.
I think we should give to charities...probably more than we do...but (for me at least) it's going to require a bit more thought.