Saints Row: The Third Cheats
There are at least 3 hard-to-find Gang Operations. One is close to the south-west corner of the map where you see 2 ship outlines on the map, the furthest ship with the giant stuffed toy has the Gang Operation.
Just a bit north-west of that you follow the coastline and notice a railway track. If you're flying then look for the wrecked train with scattered railway cars and that's the second location.
The third one is difficult to find but you need to be flying or parachute to get there. It's on top of a skyscraper in the district with the big wrestling stadium dome near the middle of the map. Count two large "city block grids" west of the dome and it's the tall rectangular building there, fly up in a chopper or VTOL and pound them hard with missiles.
If there's other ones you're missing to complete your set, follow my advice of looking for holes (ie. grey gaps in the purple coverage as you take over a sector with doing Activities & buying Properties & Stores). And of course you can spot them before they unlock by looking for tight clusters of red dots on the minimap. Even while you're working on something else, you can still get in close enough to unlock it on the map then come back for it later.
Hope that helps for the people like me who like to try to get completion.
The last gang operation is the deckers near the nuclear plant. That was my final operation.