There is a thread listing a lot of these in main forum section too - a good tip was using Strong Slot packages out of Gun Tight formations, then subbing the TE (moved outside because of the package) with another WR. From there you can audible to any other 3 WR as normal making most formations 4WR formations.
Who are your WRs? I have 99 Calvin Johnson, 96 Jerry Rice, 94 Tyreek Hill, 90 Cordarelle Patterson and 90 Chad Ochocinco. I only use Patterson on KR's and 85 rarely sees the field either, Megatron, Rice and Hill have sprinter.