Here is a Google + GIS map that displays all the congressional districts. If you zoom in then the district boundaries are *very* easy to see. Click a district to see a popup with some info about the person holding that seat.
Map link: https://goo.gl/Ops2aL
If you click the “Map Tips” link in the upper left corner then a web page will open where you can read more about the map. One of the choices on that page is “Bizarre District Maps”. Each of those map links highlights one weirdly shaped congressional district. There are examples from 21 states.
The “Map Tips” also show how anyone can make their own custom map link that highlights any district when the map opens.
Currently I am in the process of producing similar Google + GIS maps that will show all the state legislative districts for each state.
The maps are displayed by Gmap4 which is an enhanced Google map viewer that I developed.