Well, as a DA at my school, I provide the following services: information, phone numbers, resident look ups, change, selling of laundry tokens, renting out of equipment such as stuff for the rec room, vacuums and the like. I also let students in who don't have their ids and such. In addition, if you have a graveyard shift, you are suppose to do nightly rounds.
Overall, the job is very easy and pays pretty good money, I just sit here and do my homework, or post like I am doing now. Luckily, I work over at one of the upperclassmen dorms which are usually quiet. I subbed for my friend once over at a freshman dorm, and the phone was ringing of the hook, and mad people were walking in and out.