Possibly the best program for making tilesets, and it is freeware.
 

Thanks very much to Radium for the suggestion, this program does wonders!

The program is called D'Pixed, and for those of you using paint to make tilesets (YUUUUUCK!!!!!!), this program'll blow your mind how great it is for tilesets. A great thing about it is that you can edit your pallet really easily, even with some nice features like adding gradients to a pallet. It has a bilt in grid that can be toggled, that works perfect for 32x32 blocks, splitting them into 4s. I don't know all the features 'cause I'm just getting into it, but it is really rocking. Dang, my next tileset is looking so good, it even blows my own mind. :). This program also works as a gif animation program, and I'm thinking its probably many times better than Microsoft Gif Animator.

http://members.aol.com/changev/junk.htm

Also look out for the MIDI music program there, too. Really nice. :)

By the way, I suggest getting the jazz character colors assigned into the pallet before starting your tileset. Maybe I'll provide a D'Pixed pallet with the JJ2 sprite colors already assigned. Anyone interested?

Wow, I gave good advice. *print screen*

It is a nice program, I don't think even PSP can make pallette gradients or do 256 color lighten+darken effects.

Hey, that's quite nice. Thanks ;)