I've found good results with 311 that doesn't involve parking enforcement or noise complaints.

I noticed that a manhole was leaking water for a couple weeks. No one bothered to report it. I reported it to 311 and there was a whole team digging it up that night.

I saw that a crosswalk light had gone out. Again, a couple weeks and no body reported anything. I reported it, and it was fixed quite promptly.

Lot's of people have a mindset that someone else will report it, but the bystander effect is very real, and very often no one does. It takes like 3 minutes to snap a photo and report something, and doing so can improve the life of you and your neighbors.

edit: about 2 weeks ago someone dumped to full garbage bins near me, on a highly-trafficked intersection in front of a popular store in a touristy Manhattan neighborhood. For two weeks, no one bothered to report it — not anyone that lived in that building, nor any of the employees/managers of the store. Like a broken window, the two bins gathered companion trash bags, and ultimately yesterday massive pieces of plywood were dumped there. I got fed up, and reported it to 311 last night. It was all gone by noon today.