Here are my thoughts on posting your own spells:

First, once its posted on the wiki, it becomes communal SSRPG property. You can't be upset if people use it and don't credit you, and if it turns up in a class someday, feel warm and fuzzy inside but don't be shocked . I've done some awesome things in the RPG, and the wiki is a way to remember that fondly, but its also a way for other people to use it. Eventually, someone who sends their kid to a school I've created or uses a spell I explained or eats at a restaurant I named will do so without knowing that I'm the one who thought it up and may use what I created in a way I didn't intend. It's the down side of sharing, I guess, but it's also nice to see where someone can take something you started.

The other thing is that Luke knows (and agrees, I think) that I'm a big ol' stickler for being canon in our RPG. He and I will be glancing through member created spells as we stalk the wiki, and if something doesn't fit the world as JKR created and SS has expanded upon, then it will be removed. Fair warning.