I just need a super simple program like Microsoft Paint. I Google'd but I didn't find anything. Or does anyone know if Paint.Net will work on Mac? I can use that for most things, but I'd like a super simple version too.

I know of Pixlr , but it's not very simplistic (it's also only online, as far as I can tell there's no way to download it as a program)

I have never found a simple program for mac that is just like MS Paint.

What do you want to do in Paint? Edit art? Pixel art? Just experiment?

If you want to experiment, I really recommend Sketchbook Pro for drawing on a mac. It's not at all like Paint but it's something super useful to have in your toolbox. It's not free but costs less than $100. Though, I have to say, Sketchbook Pro is only good if you have a drawing tablet. The user interface is super easy to use with a tablet, but not so fun without. The only downside to Sketchbook is I haven't found a way to do pixel art (but there probably is a way, I just don't know). Other than that, I love the program because it's super natural and intuitive. I do most of my art with it.

For pixel art, you can download a variety of free programs. I haven't ever gotten into pixels but I'm sure others could help you find some.

For editing, try using Preview that comes on the mac for free! You can re-size, crop, change colors, add text, etc. It's actually quite easy and I prefer it over MS Paint.

I generally just resize things, do some pixel art, random super simple graphics like putting a couple of pictures together. I don't have a tablet, maybe around Christmas I will, but most likely not.

GIMP isn't exactly simple, but it would do everything you're looking to do, and then some.

Back in the day, OS 9 had a paint application, but I haven't seen it on OSX. There's a project on Sourceforge for this, too: http://paintbrush.sourceforge.net/

(Be careful downloading stuff from Sourceforge. Read the installer screens carefully - sometimes there's potentially unwanted programs packaged with downloads.)