Which form? Oh you mean either physical and/or cultural/traditional overlap.

"top hat", "traditional clothing", "eyes closed", "hair pull",

Just a few ideas.

"traditional clothing" - Creating that is like putting us to learn every single traditional clothing on the globe. Otherwise if it's Japan .... kimono/yukata?
"hair pull" - inducing violence?
"eyes closed" - I know I'm a tagger and that I'm obliged to tag image ... but ... this is like making us go through every single image uploaded already and tag the respective. Yes I'm complaining. ~450k images? .... ugh ... with my current irl status? It will take me .... 6 months? Maybe more ...
Otherwise you can just remove every single eye color (and the monochrome images) and you'll get images containing girls/boys with closed eyes.
"top hat" - ? ... err .... I believe the "hat" tag covers that.

is theere a way you can filter out or excluse tags then? when i look for crossovers, i look for pics containing character for different stories, and it get kind of annoying to see pics of a single chracter dressed up as another character from a different story, or a single chracter with plushies, weapons etc. from a different story.

"costume" tag? Like the one I just uploaded, http://e-shuushuu.net/image/445504/ doesn't have a correct tag to go with what she's wearing. "animal suit" doesn't fit since it's a food thing. And the others are explained in my comment there. DX

"original" (???)

Like if a member is like "Oh! Whats her name"? and you explain thats an oc. Maybe we can have an "Original" tag for these cases. Just a suggestion. =3

i believe that was suggested before and got rejected since there are way too many images to get tagged with it.
oh, here it is:
viewtopic.php?p=46270#p46270

And in reality, you can't tell if a character is original or not. Some images have a source and character, but the poster didn't know them and left them blank. If nobody else knew the source the image will just remain sourceless and/or without a character name. That still doesn't mean they're original, right? o.o

http://e-shuushuu.net/search/
Of course you can! Just input the "crossover" tag on the Tags section, or if you want to search for a specific source, input the name of the source on the Source Section. Ex., "crossover" and Puella Magi Madoka Magica source. The result will come out with MadoMagi crossovers.

I thought crossover was asking if there was a way to separate these kinds of crossovers (those with two or more characters from different sources) from these kinds of crossovers (those with a character wearing/holding/acting something from another source). Please correct me if I'm wrong.

I think he was. It won't be happening though. At least not at this point.

"pinwheel" or, *coughhackcough* "penwheel" if it doesnt exist. Sorry. I hate spelling.

I don't even know what those words mean! (aside from "cough", but as a whole word that you gave me... no idea!)

I don't think pinwheels are common enough to warrant tagging. :)

I was wondering - when Japanese people use "odango" to they mean only double buns, or does it apply for a single bun too?
and if it's for double only, shouldn't we have "hair bun" for the single thing as a child or parent tag (not sure which one it would fit under)
sorry, it's not really a suggestion, more of a question, but i wasn't sure where to put it ^^;

I think it's meant to be used for double buns, but we have started using it for the single bun as well.
We could alias it to hair bun to make it more clear though.