I know this is a long-ish list, and some of them are MUCH easier to implement than others, but none of them urgent/immediate.  They're all just "things that would be nice to have".

- hotkey to swap foreground and background colors (left-click & right-click colors)
- option to adjust the "tightness" vs. "smoothness" of the 'curve' tool.  In its current form, if you pull it very much, you end up with an arch with a tight radius and straight "legs" from the arc to the start and end points.
- ability to change the default color palette.
- contrasting border around brush/eraser/color eraser (or put a white border around the black cross-hairs) so that it shows up better, regardless of what color it's over
- MUCH larger options for color eraser - have as both tool AND "effect" where you 'select' an area, and then apply color eraser to that area
- color similarity: make the textbox have initial focus so that when you open the dialog, so that the text is already highlighted and you can type a number right away
- when editing the color palette, 'Pick Screen Color' picks the 'darkened' color if you pick a color from an inactive window (and have that 'desktop effect' turned on).