My first two itsy bitsy plugins have gone live in the plugin-store, and that's kind of fun.
The first is called "Fancypost". Basically, it's a BBCode that lets you use specific CSS attributes to style a section of your post. The CSS attributes are limited to a specific group based on safety to the layout of the forum, ease of use, and actual usefulness. For example, width and height are limited to 100% width of the forum and a specific height. Anything over the limits causes the Fancypost to scroll within the post boundaries. All of the specifically allowed CSS attributes are mentioned on the Plugin-Store page.
I have a couple more plugins coming down the pipe that have a bit more functionality. One is for "Post Templates", which lets you allow users to create an admin settable number of "templates" with an admin settable number of characters in each that can be easily inserted within a post using a convenient little button in the editor bar.
The other is a "Word Replacement" plugin as wished for here. This is a functionality that exists on my current forum, so it's something I need to create anyway. The plugin will allow the admin to set specific words that should be replaced, and what the should be replaced with. It'll also allow an admin to set whether or not a user can disable the word replacements for themselves, or if users can create word replacements that only effect themselves. It'll also allow the admin to set the maximum number of word replacements users can make, if that functionality is enabled (because you always have that one user that has to wreck things if not kept in check...).
Both of the above have made their way through my personal testing, but now need to make their way past the quality standards of the Woltlab moderators. Let's hope I'm not too awful.