Since you can add stuff to your wishlist by clicking the little + on items, why not add a little - that takes the place of the + after you click it so you can remove the item right there instead of physically removing it by clicking the item in your inventory or going into your wishlist and removing it. I tend to accidently add things to my wishlist a lot so, I thought this might be kinda handy..
Or for people that have lots of categories.. maybe when you click the + on an item to add it to your wishlist and you have categories a dropdown appears from the top of the screen (like when you click floating items) that shows the item you're adding and gives you a dropdown where you can choose what category you want it added to? Might be a little too complicated I'm not sure. You could also make it so you can cancel an item from being added to your wishlist if you click the + accidently this way.
I just thought I'd put these out there.
As much as I love this idea, we have enough trouble with the + sometimes not showing up. How are we supposed to see a tiny - ??

Yeah, I agree the + is pretty hard to see already LOL. An x would certainly be more visible than a -
I don't really like this idea. It might just be me, but once in awhlie (though moreso when I was new) I accidentally add items to my WL. It's a lot easier imo to find something on your WL and realize you don't actually want it, then remove it, rather than accidentally remove something that's on your WL and not realize it.
I don't like the categories drop-down idea either, even if it's possible somehow. I'd rather just go through and organize things where they go, especially when I mass-add things like event items to my WL, I don't want to have to click an extra button or two in a completely different part of the screen for each item, I just want to go through and click all the +s
Though I could get behind either/even both ideas if they were made optional.
I mentioned the "-" on the wishlist hover feedback thread, so I definitely support this idea.
It wouldn't be so much of an issue now with visibility since there is a little hover.
I don't really like the idea of a dropdown though. I feel like that would increase loading time.