Bearings can make all kinds of funny noises on their way out.
Removing belt driven accessories' drive belts is THE way to find out which one(s) are making noises. While the belts are off you can rotate the pullies manually, and this is also very informative. All the bearings should spin quietly by hand, and there should be *no* roughness to them at all.
My water pump ran quietly at 120k, but the bearings were a little "crunchy" when turned in one direction slowly, by hand.
My alternator was squeaking sometimes, and the bearings were VERY smooth... too smooth. An alternator should have a little resistance to turning (should not be able to spin the pulley and watch it go for 20 seconds). If an alternator's bearings are going out and they still spin smoothly, you may very well have time to save up to buy a new one or have yours reman'd. If they are crunchy, you are driving on borrowed time, but it still might last quite a while.
My a/c belt tensioner bearing was VERY rough, and sounded like valvetrain clatter, and when the engine was shut off it sounded like a big diesel rattling to a stop.
Somewhere in my transaxle a needle bearing lost a bunch of rollers, and it chewed into the gears a little and grumbled on deceleration.
Bearings failing can have all sorts of symptoms. You have to check them individually to be sure what is making what noise.