Graphics and CAD programs that treat the mouse wheel as vertical scroll.
It's dumb. It's a 1D control but there is a 2D screen to move, so what if you want to pan horizontally? The solution appears to be pressing a key as well, but now you have some movement needing a magic key and some not, and what if you really wanted to go diagonally?
The solution should be obvious: make the mouse wheel zoom in and out. With that, you can zoom and pan to wherever you want, all without any magic keys or anything, just scroll the wheel. If you need the page-analog scroll, you can add the ctrl key for vertical, shift for horizontal. That (needing a key whichever way it goes) makes more sense than sometimes needing one, and the most used option (zoom) never needs one.
Some packages let you configure the mouse wheel to however you want. I happened to try the latest Inkscape last night since someone pointed out how grown up it had got, and that doesn't let you do anything at all. You'll fart around pressing a key when you shouldn't, not when you should, moving off the bottom of the page when you meant to zoom in, and you'll bloody like it. Inkscape doesn't need to feat me using it in the near future.