We do Xi Man as well which raises over 4000 dollars every year in money and donations. I know the poster just above said that someone else already does a Xi man like competition, I would do it anyways, almost every sorority on campus here has some form of a competition like that (omega man for chi omega, king of the campus for zeta, delta man fo tri delta, etc)
Also, a good idea that I just started last year when I was philanthropy chair is Breakfast with Alpha Xi. We have changed it up a bit, but pretty much you can pick any way you want to make the competition, but the prize is to have breakfast with the lovely ladies of alpha xi delta!
Last year we had a donations competition between the fraternities for the Beta Center Orlando (our local philanthropy), using the list of things that they needed. They had a week to bring in the donations, each item havign a point value. The fraternity with the most points wins (Which last year it was TKE
This year we are doing it for HugMe a children's AIDS foundation, and we are collecting toys for the holidays. We are having a holiday party (tonight actually), and the admission is a toy or $5. They get points for the number of people who come to the event, as well as depending on type of toy. The group with the most points wins.
Hope this helps out a little.
Oh, and some other ideas that other chapters do here:
A basketball competition (ADPi)
Many many many dance competitions (zeta has one for new members only though) (ZTA, PBF, KD, and a lot of fraternities)
A spaghetti dinner (DDD)
An idol competition (BQPi)
Frats at Bat (DDD)
Cheers for Charity (ADPi)
3k run (KD)
Dodgeball (Phi Delt)
A denim sale
Hope this helps you out, I know starting a new philanthropy can be frustrating!