Well, looks like I'm diving into WP head first ... LOL. I just installed it the other day and I've written a couple plugins for it already. They're just basic. I don't think they had been done before ... I couldn't find them anyways. And I'm not sure if I'm the only one who would even use these or not, but I thought I'd share in case someone else would want them.
This plugin will display "Today" if the entry was posted today. Or it will display "Yesterday" if the entry was posted yesterday. Otherwise it will just display the weekday (i.e. Tuesday).
Trackback Popup plugin
This plugin will have a popup window displaying trackback info ... just like the comments popup window. I used Scriptygoddess' script to separate the trackbacks and comments.
I used both of these functionalities on my MT blog and wanted to have them on my WP blog too. They work so far on my blog. They're my first attempt at plugins, so hopefully I've done everything right.