Well, it depends on which of my two monitor/keyboard/mouse "stations" that I have hooked up to my machine that I'm at. If I'm on the one with the 17", then I guess I'd have to say 5 LEDs, one on monitor, one on optical mouse (bet you forgot that one), and three on the keyboard. If I'm at the other station, closer to the machine, then I have 3 on keyboard, 1 on monitor, "many" on my switch (generally only 4 active), 8-9 on my external modem, and a random assortment on my USB hubs. Also a few LEDs on the back of the machine, some extra ones I wired to parts inside the machine sticking out of the plastic front-panel, and a few more on my MSI "diagnostic bracket II" or whatever they call it. Oh yeah, a couple on my USB wireless NIC too, but I try to keep that away from my direct LOS, due to the microwaves being emitted.
Where I was living before, though, all of the darn LEDs kept me up, looked like a little city at night with the lights out. 🙁