Thought I'd post a couple of small things I did.
The first is a generic meter.
Right now I'm using it in a desert world as a heat meter. It increases slowly, hurts you when it fills, and then resets. It drains quickly if you are in water, and does not increase if you have the fire power-up.
Today I also recreated the opening/closing bridges from SMB3 Water World. I thought that was kind of fun.
One of the largest changes I've made is in the power up coding.
One thing I've done is rewritten the power up routines to handle any value through FF. So as you can see, I have added a completely new power up (birdo's egg) without changing any of the existing power ups.
I also decided to change the way the power up sprites work. I set it up so that touching a power up sprite swaps power ups always so that you can use a mushroom and become super mario even if you were fire mario before.