As the others have said, hats are good on most guys. Preferably a fedora, or something of that type. Otherwise a modest, longer necklace like link , but just one, not a whole ton. In my opinion, the only bracelets a guy could pull off are the kind made of twine or leather, like link But again, only one or two. Going overboard with jewelry can make you look tacky, and flashy jewelry just looks silly in my opinion.
watches, sunglasses, baseball hats, chain bracelets(pic) or any silver/white gold bracelets, leather bracelets, sometimes rings, businessman bag, necklace (I prefer silver and I like crosses on guys.. that if you're christian obviously), earring(s)!... don't do all of them tho! keep it simple ha ha
leather bracelets, friendship bracelets, fedora's designer sun glasses (ray bans, gucci), simple silver or gold chains, titanium rings, gauges (if you are into that) or simple studs. tattoos are als a more permanent accessory. I don't care for sleeves.
Keep in mind, this is only my personal opinion and preferences - Hats are okay if the guy wears it normally. None of that pointing it to the side crap... it's looks dumb and makes you look like a criminal. As far as jewelry, an earring is okay, but not two, unless they are small-medium gauges. For some reason, that makes it look less feminine. Bracelets (including a watch) are okay, as long as there aren't too many and they aren't girly, obviously. A couple on each wrist is fine. A necklace or two is fine. Same with rings I guess. The only "accessory" that I really think looks dumb on a lot of guys is flip flops. Some can wear them, but if your feet are really gross, then please... don't.
Hats, watches, necklaces, bracelets. The problem as I see it is that too many guys either overkill it or are terrible at selecting the actual item(s). The bit about wearing 7 necklaces at once or an oversized hat that makes you look like a circus clown -- I mean REALLY?!