Is it legal for a helicopter to land and take off in residential neiborhoods?

To legally land in a residential area, you need the permission of the owner or manager of the property. You can only do so if the event will not cause harm or damage. It is a good idea to coordinate such events with local air traffic control, especially in a highly congested urban area, and always if the landing zone is within airport controlled airspace. So, if the neighbors don't mind, and the home owner is for it, then no problem. I once picked up a friend from one wedding reception point in his back yard, and dropped him and his new bride off at the second reception venue in the parking lot of a club not too far from their home, all with his neighbors snapping tons of photos and waving at us, as I had him get their blessings before the event.