along the lines of what kappatarzan mentioned we've done something at our retreat where each member has a sheet of paper with their name printed at the top. all the sisters have an alloted amount of time to write (positive) messages to one another (we took the weekend of retreat), and at the end of the time, but not before! you can read your paper. makes for tears and smiles and hugs. if not reading the sheet of paper is too hard, have each sister bring some type of personalized container (shoebox, etc) which notes can be deposited in that have been written by the other sisters throughout the weekend.
also we did an activity called a penny for your thoughts. half the group (sister a) gets a penny and must find a sister without (sister b). sister a gives the penny to sister b for sister b's (positive but truthful / sometimes constructive) thought. these thoughts can be completely random from, you're the reason i wanted to be an adpi, to i love it when you speak up for the underdog, to you're always so positive and that makes such a difference to the chapter. they don't necessarily have to relate to the sorority but can be just general character traits that are appreciate d and valued.
if you are really lacking in sisterhood, a good idea might be to have a workshop on your goals for the group. if you are lacking in a clear set of common goals for your group, then that makes in 100 times harder to work together towards a positive end. if you need to preface this with a w orkshop where you all get together and tell why you originally wanted to be a member of abc, what you've gotten out of your membership, what you would like to achieve personally, or you can go over your creed/mission statement and what it means, how it sets you apart from other groups and what it means personally to the sisters, it might help set up a sense of community and sisterhood again.
sorry this is long, i have lots more ideas (!) so feel free to pm me if you'd like... hope some of this helps!!!
