Also a journal in my Sheezyart, but I may as well post it here:
No GIMP and Opencanvas 1, because everyone and their father knows of those two.
PixiaPixia is a Japanese drawing program. I don't like it as much as most other programs, and it is a little counter intuitive. I do like the pen smoothing though.
ArtweaverArtweaver is somewhat like Corel Painter (I'll argue that the creator yanked Corel's graphical user interface) only it's free. It emulates traditional media without sacrificing layers and filters. Fun stuff.
NekopaintNekopaint is a Japanese art program that comes in a folder which you run directly from instead of installing (the exe is a little city shaped icon). Some of the commands are Japanese but they're easy enough to get the gist of it. iI haven't figured out all the settings yet but so far its lines are incredibly smooth (think Sai lines, if you guys have heard of it). Click the first link to download the program. When you open it up it will prompt for a code but just click cancel. After thirty days the program might wig out on you, but what you can do is just delete the old folder and get a new one (CLEVER HUH).
Paint.NETI haven't tried this puppy yet but I have heard good things about it (and bad things, but that's with every program). It looks like Photoshop, and has been compared to other commercial software.
ArtrageArtrage is very good at emulating thick paint media. There's a free version and a standard version that's very cheap. Unfortunately the free version's very limited, but it was fun playing with it.
Feel free to pass this to your friends.