I called 911 recently too. I was attempting to assist a woman whose electric wheelchair had died on a steep hill and gotten her stuck. I couldn't get the thing to move, nor could the dozen other people who stopped to try and help. Those things are really heavy. I was in the process of contacting the hospital / home that the woman had come from when she, clearly starting to panic a little, directly asked me to call 911 for quick paramedic assistance. I was really hesitant to do it, but she'd specifically asked, and it was her phone (which her disability prevented her from using on her own), so I called for an ambulance. The dispatcher was a bit rude, and asked some stupid questions. One of the paramedics was kind of rude too, when they got there, but at least they figured out how to move her chair, and took responsiblity for (hopefully) getting her home safely.
I have, admittedly, called 911 a couple of times on really obviously dangerous drunk drivers I saw while at work (I drive a truck). I don't feel bad about those ... it's not the way I'd prefer to do it, but it's the only real option available to me, and those people needed to be off the road before they killed someone.