Here is the Student Union website with the Student Group directory. Student Group Directory | Student Union
Click 'List All Groups,' and there you should find a pretty comprehensive list of all student organizations.
Just a sampling of what you can participate in (a very small sampling!)
Campus YMCA: Host parties for children staying in the hospital; tutor kids in disadvantaged areas; be a big brother or sister mentor to a younger kid; go on Alternative Spring Break trips to fix houses in a rural community; educate the community about AIDs; put on science experiments for children at local junior highs and high schools...and of course, MORE.
Have you got BUZZER skills?
Be a radio host. Select the music, have your own program.
An inter-collegiate literary and art magazine founded at WashU (submissions from colleges around the nation)
The Troll Club:
"We are trolls. Help us live with it. For the promotion of troll culture."
Calling all bboys and bgirls ('breakdancing' group)!
WashU's satire and comedy student publication
For the slam poets.
As you can see from the list-- there are too many groups to list. Check them out for yourself!!!