Statistically, the most popular group on campus is D1 sports-- a full 25{4a082faed443b016e84c6ea63012b481c58f64867aa2dc62fff66e22ad7dff6c} of the student body is a student-athlete. Many more participate in club or intramural sports teams.
Sports aside, Davidson has a very active 'Environmental Action Coalition' or EAC which makes waves on campus. They have regularly sent students to events and conferences in Washington, DC!
Davidson loves the outdoors, with a popular 'Davidson Outdoors' or DO club providing weekend trips for whitewater kayaking, mountain biking, hiking, rock climbing, and tons of other activities. They also have a litany of equipment and tools to use or rent. They'll fix your bike, show you how to belay, and WAFA certify you all in one.
Other big groups on campus are the slam poetry group FreeWord, the step team Shades of Brown, the always lively DJ's of the student-run WALT radio, the DUFF ultimate frisbee team, the school newspaper The Davidsonian is always a favorite, the OOPS! improv comedy group, and probably 70 or so other groups are all active.
There is a group for everyone. In fact, most people join several!
One of the great things about Davidson is how easy it is to be involved. Sophomores are presidents of several majors clubs, and it's not unusual in the slightest. Recently a student decided to start an International Justice Mission group on campus. In under a year the group has over a hundred members and has raised thousands of dollars for their cause, and thousands of dollars in programming grants to further their IJM chapter.
Outside of groups and clubs, Davidson students have interests as varied as they are. Which means that most people drink, but many people choose other things to do. There are always things going on both up and down the hill and there isn't judgement for whatever lifestyle decisions are made. Sober or not, everyone loves getting free Chick-fil-a or Moe's at After Midnight's. Before midnight? See a free movie screening, go to a lecture, laser tag in the union, cuddle with puppies during exam time, see a slam poetry performance. There is always something going on for everyone. In a frat or independent? You'll go to the same party and no one will question it or care.
Of course, arguably the most popular tradition and activity on campus is the midnight scream. At midnight for the start of Reading Day the entire campus lets out their loudest screams in recognition of the agony that awaits.