I was the one that started the topic asking for image zoom awhile ago. I still support the idea. It's very handy in regards to critiquing pixel art and sprites, (though I never personally used it in any posts as I haven't done any pixelling for at least a year).
The one that Windy made worked well, but yeah, there was no button for it and as such either people didn't know about it or didn't feel like referring back to that topic every time they wanted to make an image zoom-able, (most people don't remember things such as that very readily). If you do implement it, I would definitely notify members via the news box.
As others have said, there are extensions for different browsers that take care of this function, but it's useful none-the-less. Surprisingly enough there are a lot of people on this forums that will never go so far as to install an add-on for a browser...considering what this forum is all about in the first place...
Anyway, if you could incorporate that script as well as include a button for it, I can almost guarantee that it would be used on a regular basis. If not that, maybe make it so that it is applied to images automatically within posts, (i.e. not avatars, signatures, etc.). I don't know how hard it would be to make a separation of these things as I personally couldn't code my way out of a cardboard-box. I'm just throwing out suggestions. That them or leave them.
Just my thoughts on the matter.
As far as the other suggestions go, I have no comments really. The [you] tag can be fun for a bit, but it will indubitably end up being an annoyance to many. Plus, most of the users already know about it by now, and that ruins most of the fun it brings in the first place. I don't mind if we do use it, but I really don't care if we don't.
