To be fair, Agape has the scissor pose. Making it the most useful item EVER.
Anyway I see a lot of Rosamund's Redemption (It's an awesome item so it's okay). Any of those cutsey leg mods (You know like the zodiacal bendy knees and Keiko's Cake leg mods). A ton of ________/Cream based outfits. I don't like saying overused or abused because it works most of the time so I don't really notice it until waaaaaaaaay after I see it.
Agreed on the lusty sheen item being abused though. I see the sheen as a parody pose so people using it so seriously gets me at times .-. For me I just liked the book, hair and background so yeah
Little Lucie ( I know , I am wearing it too, but it ' s the only good blood-dripping knife around emotion_awesome ) .
Band of Bremen .
Keiko ' s Cake.
Wed To Darkness .
Those are a few that I think are used quite a lot .
It's not so much the item as a whole, but certain poses from items. Like, the scissors from Agape are everywhere, but you never really see anyone using the face or the sword or the letter. Using less common poses of super-common items is actually a really fun way to go about making an avatar.
On topic...umm...Can't really say. I tend to see Oisin a lot, and with the release of the latest MC's, I see a lot of avatars with the arms from Dark Omen, but they'll fade out shortly. I'd say that the most abused items are the cash shop/RIG items that have come out most recently and are considered "high-end," like the Rosamund and Reve recolours.