Fundraising...What to do

I am facing the dilemna that many parents face I am sure.  How much fund raising do you let your child do.  I feel like on occasion we are constantly asking for money from friends and family.  I have so far decided to put my foot down this year and let him only do the scout ones.  But I am pretty sure once his school does theirs he will convince me to let him do a little bit.  So if anyone has any ideas on how to handle this let me know....  I know it is important and it goes for a good cause.  But I also know how tight money is in my household, and how hard it is to say no to a cute 8 year old boy.