Yeah there's all kinda of weird noises they make. If it's very cold out, like 15 or lower, when I start with a cold engine it makes this awful noise when the engine catches for maybe 1-2 seconds. That sounds like the belt though.
Only "buzz" I get comes from my transmission. For example, a shift from PARK down to DRIVE will produce a light, 1 second long buzz. I'm not positive what that is, but I see nearly 50% of all JK's do it, and a lot of TJ's too. I've also seen this in a Charger, and a couple T&C vans. Whatever that is, it's a Chrysler thing.
Haven't seen it on the JK, but my girlfriend's Cobalt buzzes every start-up. It's the power steering pump. I've replaced it twice. Must be a Chevy thing
that's also something to keep in mind though.
I'm about to do all kinds of crap to my Jeep. Oil, transfer case, axles, etc. I'll get a fresh look at what's under the passenger seat/floor and what could possibly buzz in front of the passenger firewall.