As a chapter you will likely have large group meetings that have a special focus/theme in addition to your weekly chapter meetings.
Chapter Prayer Meeting: Devote a whole large group meeting for an extended time of prayer. Divide the time into periods of adoration, thanksgiving, confession, and intercession for chapter concerns and world missions. Intersperse these prayer times with selected Scripture and songs. One form of this is "The Concert of Prayer." (A detailed guide can be obtained through InterVarsity Missions). This requires strong leadership and clear instructions about the flow of the prayer time.
Evangelistic Meetings: The basic pre-requisite is for chapter members to commit themselves to bring non-Christian friends to the large group meeting. Publicize broadly! The use of drama, skits, clowning, etc., can be useful in communicating the gospel. Student testimonies, carefully chosen and prepared can add to the message. Choose an evangelistic speaker who can relate the gospel to issues relevant to non-Christian college students and who can call for a clear response (an invitation to receive Christ.) Be sure the leaders are "evangelistically sensitive." That is, don't expect everyone to pray or know the songs, and don't use Christian jargon.
Mini-Missions Conference: Set up the room with five or six tables to serve as stations. Each station can either represent a particular part of the world or a particular mission agency. Divide the whole group into five or six small groups. Have them rotate around to the different stations, spending 15 minutes at each one. Then allow some free time at the end for students to get further information from the station which interests them the most.
Evangelistic Resource Fair: Once again, set up several tables as stations. Each station can offer types of evangelistic materials or training in evangelism (e.g. leading an Evangelistic Bible Study, Demonstration of a Dorm talk, writing a personal testimony, role-play of a gospel presentation). You can either allow people to move around freely from station to station or have them rotate through the various stations in small groups.
Fellowship Meetings: You may want to occasionally devote an entire chapter meeting to a social event, such as a Christmas party, picnic, volleyball, banquet, coffee house (with an open mike), costume party, ice cream social, etc. These events can add much to building a sense of community in the life of the chapter.
Other possibilities include a Hunger Awareness Dinner, (see booklet "Hunger Awareness Dinners" by Aileen Van Bailen, Herald Press, Scottdale, PA). Christmas Caroling (practice then go out on campus or in a neighborhood), Faculty Nite (invite all known Christian faculty), Christian Art Festival (presentation of visual and performing arts by chapter members), and other events related to special holidays, campus events, or national concerns (e.g. Black History Month).