At Michigan every fraternity puts up banners on their houses saying RUSH TKE, JOIN EX, PLEDGE BETA etc. Then there are all the open parties that they have during orientations, welcome week and the first 2 weeks of school before rush starts. There is also Festifall were all campus orgs can have a table set up talking about their group and a good majority of them do this (Winter Fest also). Sororities also so Festifall and Winter Fest, we have the open house informational, send out a video during the summer, chalk the campus.
All Greeks houses paint The Rock, put up flyers and participate in Greek Move-In, where members of greek houses help move in students who are going to live in the dorms.
*Controversial* Sororities also get themselves out by being "Door Whores" at Fraternity Rush parties. All you do is greet and sign the PMN members in and tell them to tell the girls they know about their org. Serenading is also done. AT UM greeks let themselves be known.