A Cappella, and singing in general in choirs/glee clubs/etc are HUGE at Amherst. However, there are many other things students to do. There's a new Center for Community Engagement for students interested in community services, several tutoring groups for helping local poor high school/middle school students, a very vibrant jazz scene (many jazz bands/ensembles), several NCAA athletic teams obviously (30% of the school competes here), intramural basketball is quite popular, a zillion publications (literary reviews, humor magazines, journals of punditry), an outing club to kayak/hike/ski/climb through the great outdoors around here, a popular improv comedy group, religious groups (ie Hillel with Friday Night Shabbat), cultural groups (ie German House with its popular weekly coffee), and so much more a student can do here.
I was involved with a magazine called the Indicator as co-editor-in-chief. We collected submissions of Maureen Dowd-esque 800-1600 words opinion pieces to print in the campus journal of social and political thought. The bi-weekly publication also had a popular humor section in the back with cartoons, mock advertisments, etc.
Students in dorms tend to leave their doors open. Amherst is a pretty trusting place. Basketball is extremely popular at Amherst because of the great success of the team. Football is somewhat popular. Other sports aren't that well attended. We get speakers on topics as diverse as physics, philosophy, geology, fine arts, and religion. We've had CIA directors and Supreme Court justice. A speaker can be found just about every day so most talks aren't that well attended. However, controversial speakers (ie John Bolton and Ann Coulter) can drew several hundred students. There are a few students very involved and in love with theater at Amherst. However, at the singing college, there is generally little interest in theater here.
The casual dating scene is, unlike at a big university, pretty non-existent at Amherst. There is a very vibrant hookup scene, especially within the athletic community. Moreover, there are a few very close relationship (I have a few friends who are engaged!). Basically, people at Amherst are either basically married or basically "f***-buddies". There's little in between. It'd be somewhat socially out of place here to ask someone out to a Friday night movie.
I met most of my closest friends through freshman orientation/freshman housing. And I'd say that's how most friends here meet. However, I met other close friends through random occurrences such as meeting through a mutual acquaintance or a sports economics class.
If I'm awake at 2am on a Tuesday I'm either studying or having a late-night conversation with my roommates about anything ranging from women to philosophy over some late night beers.
There are many annual traditions. There's a spring concert, spring carnival, spring formal, homecoming game, luau party, "Hollywood" party, the "endless summer" party, Crossett Christmas, and, of course, D3 March Madness.
I'd say most people party here on Friday and Saturday exclusively. The more adventurous do Thursday too. And, for seniors, Wednesday is bar night.
Frats/sororities don't have many brothers/sisters. (They're all underground) However, for the people who join them, they can provide a community and great relationships (and, of course, hazing).
The standard Amherst Saturday is crowding into a Triangle/Social Dorm party with hundreds of other drunk kids, finding the keg, getting the last drops of bad Natty Ice, and coming back either disappointed (for not hooking up) or disappointed the next morning (for having a great morning, but hangover and awkward week coming up). However, though drinking is dominant here, there is a substance free scene here. Plus, there are always plays/concerts/poetry jams/etc. on the weekends. Amherst Cinema, a great artsy theater, is walking distance, and, for me at least, often a great weekend excursion.
Most people tend to stick to all the stuff to do on-campus. However, Northampton is a cute little town that's only 45 min away, Boston's only 2 hr away and NY's only 3 hrs away and can provide great relief. For me, the great nature of the Pioneer Valley was my escape from Amherst. The Connecticut provides great kayaking/canoeing opportunites, the Deerfield is a great place to tube, and there are many great places around here to rock climb/ski/hike.