https://www.romhacking.net/hacks/9932/
that's my latest Super Mario Bros 3 hack, Super Froggio Bros, which places frogsuit powerups in the normal ? boxes all over the game. this is a simple concept, but somehow nobody else has done it until now, as far as i know. and that may be because it's a lot more complicated under the hood to do it, than you might think. not super complicated, but definitely not a simple thing to do.
this follows my other similar hacks-
Super Hammer Bros 3- same idea but with hammer suits all over the game. this is my first one, and there are two versions. version A is 'purist' (like the current frog suit hack), and version B does a few things like bringing in the Japanese version's damage to mario system (and accompanying suit flying off effect), making the game slightly harder, while on the other hand buffing the suit a bit by allowing the hammers to damage koopa kids (they can't, normally), and a few other changes.
Super Tanooki Bros 3- again, same idea but with tanooki suits. version A again is the purist version, just adds the suits, no other changes, and for version B i got a lot more creative by buffing the suit in various ways (you can smash bricks from above by landing on them with statue, statue comes out quicker, tail dispels enemy projectiles, kills more enemies, you can use tail under water, and other changes outlined in the .txt). i think version B of this one is my favorite hack and actually makes the tanooki suit fun enough to compete with hammer suit, whereas normally i think tanooki suit is fairly boring.
last and least is Smallio Bros version A, which simply removes all powerups (except starman), leaving mario permanently small. other people have made hacks accomplishing this but i wanted to do my own and i think mine is maybe the most elegant of all that i saw. i have versions B and C of 'smallio bros' hacks mostly done and they are way more interesting and creative, i'll have to finish them up some day and put them out.
if you check any of these things out and like them, consider leaving a review at romhacking.net if you have an account, it kind of bums me out that none of my hacks get any comments there. you don't have to though!