Hello there! I'm new to this wikia, but as an avid fan of the Super Monkey Ball series, I hope to contribute plenty of content in the coming weeks. For the time being though, I've spent a fair few hours of today tidying up and adding content to the Super Monkey Ball: Banana Splitz page of this wikia. I've also added comprehensive level lists for each difficulty. Each includes an overview of the worlds within it, photographs for each level, a basic outline of each level, and the total banana counts for each level. Finally, I've replaced the old page picture for Super Monkey Ball 1/2/Deluxe's Master difficulty page with a higher-quality one taken directly from the game (and added a passable-quality image for Ultimate mode).
I think it'd be good to create individual pages for each difficulty for all of the games in the series thus far. It'd take a fair bit of time to get done, but I'd be happy to work on it. I can offer level lists, information, and images for the original Naomi Monkey Ball, Super Monkey Ball 1, 2, Deluxe, Adventure, Banana Blitz, and, of course, Banana Splitz. I'm afraid I can't help with Step & Roll, 3D, Touch & Roll, Jr., or any of the other more minor releases.
I'm also planning to try and directly rip the Banana Splitz soundtrack over the coming days as, from what I've searched, nobody else has put it up online. I don't think that sort of content is wikia material (nor strictly legal, although I don't think under fair non-profit usage SEGA will mind getting free publicity for their work), but I might link to it here when it's done.
If you want to quickly jump to the pages I've made major edits to, here they are: