More important to me (as a former employee of a popular internet site) than songs or fancy designs are:
1. Usability - how easy is it to use the features and get around?
2. "Three clicks to paydirt" - is the important info within three clicks?
3. Content:
a. Is the copy (words) is relevant?
b. Is the site intended for members or visitors? Some chapter sites have virtually no info or descriptions. It would be cool to read about how much money you raised for X charity, that three of your members are on Student Government, that you have a 3.10 GPA, etc. It's virtually free PR!!
c. Pictures often show more than you can tell, but captions or album headers can tell your story (formals, philanthropy, sisterhood events). Random pictures of people in costumes or sitting around don't tell you much, but sharing that this pic is from a recruitment skit where you performed "We Go Together" from Grease, that these shots are from Greek Week when you danced to "I Got A Feeling", or that this photo is from "campus clean-up 2009", tells visitors so much more about your chapter.